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Linear_Equations_And_Systems_Word_Problems/746010: In one week, Fearless Frank drove 100 miles on the freeway and 150 miles in town. His car consumed 18.2 gallons of gasoline. The next week his journeys took him over 180 miles of freeway and 30 miles of local driving, and he used only 10.9 gallons of gas. What were his highway m.p.g. and his local m.p.g.?
1 solutions

Answer 454105 by josmiceli(9685) About Me  on 2013-05-07 14:52:34 (Show Source):
You can put this solution on YOUR website!
The key is to see that ( miles driven ) / ( miles / gallon ) = gallons
I can say:
Let +a+ = mpg on the highway
Let +b+ = mpg in town
(1) +100+%2F+a+%2B+150+%2F+b+=+18.2+
(2) +180+%2F+a+%2B+30+%2F+b+=+10.9+
-----------------------------
(1) +1000+%2F+a+%2B+1500+%2F+b+=+182+
(2) +1800+%2F+a+%2B+300+%2F+b+=+109+
------------------------------
Multiply both sides of (2) by +5+
and subtract (1) from (2)
(2) +9000+%2F+a+%2B+1500+%2F+b+=+545+
(1) +-1000+%2F+a+-+1500+%2F+b+=+-182+
+8000%2A%281%2Fa%29+=+363+
+a+=+8000+%2F+363+
+a+=+22.039+
and
(2) +1800+%2F+22.039+%2B+300+%2F+b+=+109+
(2) +81.673+%2B+300%2Fb+=+109+
(2) +300%2Fb+=+27.327+
(2) +b+=+300+%2F+27.327+
(2) +b+=+10.978+
-----------------
His highway m.p.g. was about 22
and his local m.p.g. was about 11
-----------------
check:
(1) +100+%2F+22.039+%2B+150+%2F+10.978+=+18.2+
(1) +4.537+%2B+13.664+=+18.2+
(1) +18.2007+=+18.2+
close enough



Reduction-of-unit-multipliers/746011: a water hose can fill a 1 quart bottle with water in 2.2 seconds; I need to buy a pond pump but its flow rates are given in gallons per hour. what size pump should I purchase to the nearest 100 GPH?
1 solutions

Answer 454103 by josmiceli(9685) About Me  on 2013-05-07 14:32:10 (Show Source):
You can put this solution on YOUR website!
You want an answer in ( gallons / hr ), so
in terms of just units:
( quarts / sec ) x ( gallons / quart ) x ( sec / min ) x ( min / hr ) = ( gallons / hr )
-----------------------
This is easier to see if you pull out all the like units:
( quarts / quarts ) x ( sec/ sec ) x ( min / min ) x ( gallons / hr ) = ( gallons / hr )
-------------
Using your numbers:
+%28+1%2F2.2+%29%2A%28+1%2F4+%29%2A%28+60%2F1+%29%2A%28+60%2F1+%29+
+3600+%2F+%28+2.2%2A4+%29+=+409.1+
To the nearest 100 GPH, you need a 400 GPH pump


Rate-of-work-word-problems/745788: Peter and Paul can do a certaion job in 3 hours. On a given day, they worked together for 1 hour then Paul left and Peter finishes the rest of the work in 8 more hours. How long will it take Peter to do the job alone?
1 solutions

Answer 454019 by josmiceli(9685) About Me  on 2013-05-06 23:25:05 (Show Source):
You can put this solution on YOUR website!
If they can do the whole job in 3 hrs working
together, then in 1 hour, they can do +1%2F3+
of the job
That means there is 2/3 of the job left to do
-----------------
Then, ( Peter's rate of working ) x ( 8 hrs ) = 2/3
Let +R%5B1%5D+ = Peter's rate of working
+8R%5B1%5D+=+2%2F3+
+R%5B1%5D+=+2%2F24+
+R%5B1%5D+=+1%2F12+
Peter would take 12 hrs to do the job alone
check:
----------
Let +R%5B2%5D+ = Paul's rate of working
+R%5B1%5D+%2B+R%5B2%5D+=+1%2F3+
+1%2F12+%2B+R%5B2%5D+=+1%2F3+
+R%5B2%5D+=+4%2F12+-+1%2F12+
+R%5B2%5D+=+1%2F4+
In +1+ hr,
+1%2F12+%2B+3%2F12+=+x%2F1+
+x+=+1%2F3+
So, +2%2F3+ of the job is left
Peter does
+1%2F12++=+%282%2F3%29+%2F+8+
+1%2F12+=+1%2F12+
OK



Rate-of-work-word-problems/745794: father and a his son can dig a well if the father works 6 hours and his son works 12 hours or they can do its if the father works 9 hours and the son works 8 hours. How long will it take for the son to dig the well alone?
1 solutions

Answer 454007 by josmiceli(9685) About Me  on 2013-05-06 22:10:56 (Show Source):
You can put this solution on YOUR website!
You can add their rates of digging to get their rate
working together
Let +R%5B1%5D+ = father's rate of digging
Let +R%5B2%5D+ = Son's rate of digging
--------------------------------
In general, I can say that:
( time spent digging ) x ( rate of digging ) = fraction of job done
---------------
given:
(1) +6R%5B1%5D+%2B+12R%5B2%5D+=+1+
(2) +9R%5B1%5D+%2B+8R%5B2%5D+=+1+
( note that +1+ means entire job done )
----------------
Multiply both sides of (1) by +3+ and
both sides of (2) by +2+
Then subtract (2) from (1)
----------------------
(1) +18R%5B1%5D+%2B+36R%5B2%5D+=+3+
(2) +-18R%5B1%5D+-+16R%5B2%5D+=+-2++
+20R%5B2%5D+=+1+
+R%5B2%5D+=+1%2F20+
-----------------
(1) +6R%5B1%5D+%2B+12R%5B2%5D+=+1+
(1) +R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+
(1) +R%5B1%5D+%2B+2R%5B2%5D+=+1%2F6+
(1) +R%5B1%5D+%2B+2%2A%281%2F20%29+=+1%2F6+
(1) +R%5B1%5D+=+1%2F6+-+1%2F10+
(1) +R%5B1%5D+=+5%2F30+-+3%2F30+
(1) +R%5B1%5D+=+2%2F30+
(1) +R%5B1%5D+=+1%2F15+
-----------------
The son would take 20 hrs working alone
check:
(2) +9R%5B1%5D+%2B+8R%5B2%5D+=+1+
(2) +9%2A%281%2F15%29+%2B+8%2A%281%2F20%29+=+1+
(2) +9%2F15+%2B+8%2F20+=+1+
(2) +36%2F60+%2B+24%2F60+=+60%2F60+
(2) +1+=+1+
OK








Mixture_Word_Problems/745797: they combine 15lbs of a mix that is 60% peanuts with 10lbs of a second mix that is 30% peanuts. How many pounds of peanuts are in the combined mix?

1 solutions

Answer 453996 by josmiceli(9685) About Me  on 2013-05-06 21:32:49 (Show Source):
You can put this solution on YOUR website!
+.6%2A15+=+9+
+.3%2A10+=+3+
+9+%2B+3+=+12+
12 pounds of peanuts are in the mix


Travel_Word_Problems/745513: THE HEIGHT OF THE ROCKET AFTER t SECONDS WHEN FIRED STRAIGHT UP WITH AN INITIAL SPEED OF 150FT PER SECOND FROM AN INITIAL HEIGHT OF 2 CAN BE MODELED BY THE FUNCTION: s(t)=-16t^2+150t+2
WHEN WILL THE ROCKET BE 300ft?
WHAT IS THE MEANING OF THE Y INTERCEPT
WHEN WILL IT REACH THE GROUND?
I AM UNSURE OF HOW TO START THE PROBLEM. DO I USE THE QUADRATIC FORMULA?

1 solutions

Answer 453866 by josmiceli(9685) About Me  on 2013-05-06 11:01:46 (Show Source):
You can put this solution on YOUR website!
+s%28t%29++=+-16t%5E2+%2B+150t+%2B+2+
+s%28t%29+ is the height of the rocket from the ground
If you want the height to be +300+ ft, then
+s%28t%29+=+300+
+300++=+-16t%5E2+%2B+150t+%2B+2+
+-16t%5E2+%2B+150t+-+298+=+0+
Divide through by +2+
+-8t%5E2+%2B+75t+-+149+=+0+
Use quadratic wquation
+t+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+
+a+=+-8+
+b+=+75+
+c+=+-149+
+t+=+%28-75+%2B-+sqrt%28+75%5E2+-+4%2A%28-8%29%2A%28-149%29+%29%29+%2F+%282%2A%28-8%29%29+
+t+=+%28-75+%2B-+sqrt%28+5625+-+4768+%29%29+%2F+%28-16%29+
+t+=+%28-75+%2B-+sqrt%28+857+%29%29+%2F+%28-16%29+
+t+=+%28-75+%2B+29.275%29+%2F+%28-16%29+
+t+=+-45.725%2F%28-16%29+
+t+=+2.858+ sec
In 2.858 sec the height of the rocket will be 300 ft
------------------
I have to run now- check my math. The method
should be OK


Money_Word_Problems/745328: In 1980 the average price of a home in Brainerd County was $95,000. By 1987 the average price of a home was $123,000. Which of the following is a linear model for the price of a home, P in brainerd County in terms of a year, t? let t=0 correspond to 1980.
Answers:
A) P=123,000-4000t B) P=4000t+95,000
C) P= 123,000- 28,000t D) P= 28,000t + 95,000
1 solutions

Answer 453803 by josmiceli(9685) About Me  on 2013-05-05 20:11:51 (Show Source):
You can put this solution on YOUR website!
Use the point slope formula:
+P+ is plotted on the vertical axis
+t+ is plotted on the horizontal axis
+%28+P+-+95000+%29+%2F+%28+t+-+0+%29+=+%28+123000+-+95000+%29+%2F+%28+7+-+0+%29+
+%28+P+-+95000+%29+%2F+t+=+28000+%2F+7+
+%28+P+-+95000+%29+%2F+t+=+4000+
+P+-+95000+=+4000t+
+P+=+4000t+%2B+95000+
The answer is B)


Travel_Word_Problems/745124: When Mr. Gomez drives his car to work, the trip takes 30 minutes. When he rides the bus, it takes 45 minutes. If his average driving speed is 12 mph faster than the average speed of the bus, find the distance he travels to work.

1 solutions

Answer 453738 by josmiceli(9685) About Me  on 2013-05-05 13:07:44 (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance to work
Let +s+ = the speed of the bus
Convert minutes to hours
By car:
(1) +d+=+%28+s+%2B+12+%29%2A%281%2F2%29+
By bus:
(2) +d+=+s%2A%283%2F4%29+
------------------
Substitute (2) into (1)
(1) +s%2A%283%2F4%29+=+%28+s+%2B+12+%29%2A%281%2F2%29+
Multiply both sides by +4+
(1) +3s+=+2%2A%28+s+%2B+12+%29+
(1) +3s+=+2s+%2B+24+
(1) +s+=+24+
Substitute this result into (2)
(2) +d+=+24%2A%283%2F4%29+
(2) +d+=+6%2A3+
(2) +d+=+18+
The distance to work is 18 miles


Functions/745110: The height s, in feet, of a rock thrown upward at an initial speed of 64 ft/sec from a cliff 50 ft above an ocean beach is given by the function s(t)=-16t^2+64t+50, where t is the time in seconds. Find the maximum height above the beach that the rock will attain.
1 solutions

Answer 453737 by josmiceli(9685) About Me  on 2013-05-05 12:56:57 (Show Source):
You can put this solution on YOUR website!
The maximum height of this parabolic curve is
+s%5Bmax%5D+ when +t+=+-b%2F%282a%29+ and
the equation has the form:
+s%28t%29+=+at%5E2+%2B+b%2At+%2B+c+
In your equation,
+s%28t%29+=+-16t%5E2+%2B+64t+%2B+50+
+a+=+-16+
+b+=+64+, so
+t+=+-64+%2F+%28+2%2A%28-16%29%29+
+t+=+-64+%2F+-32+
+t+=+2+ sec
--------------
Now find +s%282%29+ which is the maximum height
+s%282%29+=+-16%2A2%5E2+%2B+64%2A2+%2B+50+
+s%282%29+=+-64+%2B+128+%2B+50+
+s%282%29+=+114+ ft
The maximum height is 114 ft
Here's the plot:
+graph%28+400%2C+400%2C+-2%2C+5%2C+-10%2C+130%2C+-16x%5E2+%2B+64x+%2B+50+%29+


Travel_Word_Problems/745117: Megan is going on a long distance road trip. She drives for 14 miles before being able to travel at a constant speed using cruise control. The equation y = 70x + 14 can be used to find her total distance traveled. If y is the total number of miles driven, and x is the number of hours driven after reaching 14 miles, which statement best describes the rate of change in the distance traveled?
1 solutions

Answer 453736 by josmiceli(9685) About Me  on 2013-05-05 12:45:08 (Show Source):
You can put this solution on YOUR website!
The rate of change of the distance traveled is
the slope of the equation, which is:
( change in y ) / ( change in x ) = 70 mi/hr


Mixture_Word_Problems/744992: Wilma went to the local market and bought 3 lemons and 5 oranges for $2.40.The same day and for the same price ,Fran bought 4 lemons and 7 oranges for $3.31.What was the prices per lemon and the price per orange?
Answer is $o.25 per lemon and $.33 per orange
1 solutions

Answer 453642 by josmiceli(9685) About Me  on 2013-05-04 21:46:45 (Show Source):
You can put this solution on YOUR website!
Let +a+ = price of a lemon
Let +b+ = price of an orange
given:
(1) +3a+%2B+5b+=+240+ ( in cents )
(2) +4a+%2B+7b+=+331+ ( in cents )
--------------------
Multiply both sides of (1) by 4
and both sides of (2) by 3
Then subtract (1) from (2)
(2) +12a+%2B+21b+=+993+
(1) +-12a+-+20b+=+960+
+b+=+33+
and
(1) +3a+%2B+5%2A33+=+240+
(1) +3a+=+240+-+165+
(1) +3a+=+75+
(1) +a+=+25+
25 cents /lemon and
33 cents/orange



Miscellaneous_Word_Problems/744942: A herd of 575 deer is introduced onto a small. island. At first the herd increases rapidly, but eventually food resources dwindle and the population declines. suppose that the number of deer after t years is given by the following formula
N(t)= -t^4 + 2t^2 + 575
please show a step by step on how you got your answer
1 solutions

Answer 453639 by josmiceli(9685) About Me  on 2013-05-04 21:36:21 (Show Source):
You can put this solution on YOUR website!
You didn't finish the question


Travel_Word_Problems/744989: 1) At 6 a.m., a passenger train and a freight train leave stations that
are 360 miles apart and travel toward each other. The passenger train averages twice the speed of the freight train. At 10 a.m., the trains pass each other.


Write and solve an equation to find the average speed of each train
1 solutions

Answer 453638 by josmiceli(9685) About Me  on 2013-05-04 21:27:44 (Show Source):
You can put this solution on YOUR website!
Think of one train as standing still and the
other approaching at the sum of their speeds
( it doesn't matter which train is moving )
--------------------------------------
Let +s+ = the speed of the slower train
+2s+ = the speed of the faster train
The time the moving train is traveling is
10 AM minus 6 AM = +4+ hrs
----------------------------
+360+=+%28+s+%2B+2s+%29%2A4+
+360+=+12s+
+s+=+30+
+2s+=+60+
The average speed of the freight train is 30 mi/hr
The average speed of the passenger train is 60 mi/hr
---------------
check:
freight train:
+d%5B1%5D+=+30%2A4+
+d%5B1%5D+=+120+
---------------
passenger train:
+d%5B2%5D+=+60%2A4+
+d%5B2%5D+=+240+
--------------
+d%5B1%5D+%2B+d%5B2%5D+=+120+%2B+240+
+d%5B1%5D+%2B+d%5B2%5D+=+360+ mi
OK


Mixture_Word_Problems/744940: three solutions contain a certain acid. the first contains 15% acid, the second 35%, and the third 40%. A chemist wishes to use all three solutions to obtain a 75-liter mixture containing 34% acid. If the chemist wants to use twice as much of the 35% solution as of the 40% solution, how many liters, to the nearest 10th, of each solution should be used?
1 solutions

Answer 453617 by josmiceli(9685) About Me  on 2013-05-04 16:43:03 (Show Source):
You can put this solution on YOUR website!
Let +a+ = liters of 40% solution needed
+2a+ = liters of 35% solution needed
Let +b+ = liters of 15% solution needed
---------------
+.4a+ = liters of acid in 40% solution
+.35%2A2a+=+.7a+ = liters of acid in 35% solution
+.15b+ = liters of acid in 15% solution
----------------
(1) +a+%2B+2a+%2B+b+=+75+
(2) +%28+.4a+%2B+.7a+%2B+.15b+%29+%2F+75+=+.34+
----------------
(1) +3a+%2B+b+=+75+
and
(2) +1.1a+%2B+.15b+=+.34%2A75+
(2) +1.1a+%2B+.15b+=+25.5+
(2) +110a+%2B+15b+=+2550+
----------------
Multiply both sides of (1) by +15+
and subtract (1) from (2)
(2) +110a+%2B+15b+=+2550+
(1) +-45a+-+15b+=+-1125+
+65a+=+1425+
+a+=+21.9+
+2a+=+43.8+
and, since
(1) +3a+%2B+b+=+75+
(1) +3%2A21.9+%2B+b+=+75+
(1) +65.8+%2B+b+=+75+
(1) +b+=+9.2+
21.9 liters of 40% solution are needed
43.8 liters of 35% solution needed
9.2 liters of 15% solution are needed
--------------
check:
(2) +%28+.4a+%2B+.7a+%2B+.15b+%29+%2F+75+=+.34+
(2) +%28+1.1%2A21.9+%2B+.15%2A9.2+%29+%2F+75+=+.34+
(2) ++24.1+%2B+1.4+=+.34%2A75+
(2) +25.5+=+25.5+
OK


Mixture_Word_Problems/744895: How much pure water must be mixed with 2 pints of 50% developer to produce a mixture that is
31% developer
1 solutions

Answer 453616 by josmiceli(9685) About Me  on 2013-05-04 16:20:51 (Show Source):
You can put this solution on YOUR website!
Let +w+ = pints of water needed
+.5%2A2+=+1+ pint of developer in 50% solution
--------------
+1+%2F+%28+2+%2B+w+%29+=+.31+
+.31%2A%28+2+%2B+w+%29+=+1+
+2+%2B+w+=+1%2F.31+
+w+=+3.2258+-+2+
+w+=+1.2258+ pints
--------------------
check:
+1+%2F+%28+2+%2B+w+%29+=+.31+
+1+%2F+%28+2+%2B+1.2258+%29+=+.31+
+1+%2F+3.2258+=+.31+
+.31+=+.31+
OK


logarithm/744927: If log(base 3)2 = x simplify each logarithm
a) log(base 3)8
b) log(base 3)24
c) log(base 3)√2
d) log(base 3)6√2

Can you please help me out? Thanks so much in advance:)
Can you also show all the steps because it would help me understand :)
1 solutions

Answer 453615 by josmiceli(9685) About Me  on 2013-05-04 16:12:49 (Show Source):
You can put this solution on YOUR website!
How well do you understand what logs are?
If I say +a%5Eb+=+c+, then
+a+%7D%7D+is+the+base%0D%0A%7B%7B%7B+b+ is the log
+c+ is the result
So I can rewrite this exactly as:
+log%28+a%2Cc+%29+=+b+
----------------
The general rules are:
+log%28+a%2Ca+%29+=+1+
+log%28+a+%29+%2B+log%28+b+%29+=+log%28+a%2Ab+%29 ( the base can be 10, or anything else )
+log%28+a%5E2+%29+=+2%2Alog%28a%29+ ( again, the base can be anything )
----------------
+log%28+3%2C2+%29+=+x+
a)
+log%28+3%2C8+%29+=+log%28+3%2C+2%5E3+%29+
+log%28+3%2C+2%5E3+%29+=+3%2Alog%28+3%2C2+%29+
+3%2Alog%28+3%2C2+%29+=+3x+
b)
+log%28+3%2C24+%29+=+log%28+3%2C+3%2A8+%29+
+log%28+3%2C+3%2A8+%29+=+log%28+3%2C3+%29+%2B+log%28+3%2C8+%29+
++log%28+3%2C3+%29+%2B+log%28+3%2C8+%29+=+1+%2B+3x+
c)
+log%28+3%2C+sqrt%282%29%29+=+log%28+3%2C+2%5E%281%2F2%29%29+
++log%28+3%2C+2%5E%281%2F2%29%29+=+%281%2F2%29%2Alog%28+3%2C+2+%29+
+%281%2F2%29%2Alog%28+3%2C+2+%29+=+x%2F2+
d)
+log%28+3%2C+6%2Asqrt%282%29+%29+=+log%28+3%2C6+%29+%2B+log%28+3%2C+sqrt%282%29+%29+



+x+%2B+1+%2B+x%2F2+=+1+%2B+%283x%29%2F2+



Travel_Word_Problems/744932: two airplanes start at the same time and fly toward each other from points 200 km apart at rates of 350 km/h and 400km/h when will they meet
1 solutions

Answer 453614 by josmiceli(9685) About Me  on 2013-05-04 15:49:57 (Show Source):
You can put this solution on YOUR website!
Think of one plane as standing still and the
other approaching at the sum of their speeds.
Equation for the moving plane:
+200+=+%28+350+%2B+400+%29%2At+
+200+=+750t+
+t+=+200%2F750+
+t+=+.2667+ hrs
+.2667%2A60+=+16+ min
They will meet in 16 min


logarithm/744755: Show that log(base 1/c)x = log(base c)1/x

Can you please help me out with this question? Thanks so much in advance:)
Can you show all the steps because it will help me understand more thanks
1 solutions

Answer 453525 by josmiceli(9685) About Me  on 2013-05-03 19:53:51 (Show Source):
You can put this solution on YOUR website!
Prove:
+log%28+1%2Fc%2C+%28x%29+%29+=+log%28+c%2C+%281%2Fx%29+%29+
I will say that
+a+=++log%28+1%2Fc%2C+%28x%29+%29+
+b+=+log%28+c%2C+%281%2Fx%29+%29+
Now I can say
(1) +%28+1%2Fc+%29%5Ea+=+x+
(2) +c%5Eb+=+1%2Fx+
-----------------
(2) +1%2F%28+c%5Eb+%29+=+x+
Now I can say
+1%2F%28+c%5Eb%29+=+%28+1%2Fc%29%5Ea+
This is the same as
+%28+1%2Fc+%29%5Eb+=+%28+1%2Fc+%29%5Ea+
+a+=+b+
+log%28+1%2Fc%2C+x+%29+=+log%28+c%2C+1%2Fx+%29+


Quadratic_Equations/744337: Karens Backyard has a width of 25 meters and a length of 35 meters. SHe wants to put a rectangular flower garden in the middle of the backyard leaving a strip of grass of uniform width around all sides of the flower garden. If she wants to have 324 square meters of grass what will be the width and length of the garden
1 solutions

Answer 453270 by josmiceli(9685) About Me  on 2013-05-02 15:59:21 (Show Source):
You can put this solution on YOUR website!
Let +x+ = the uniform width of the grass border
The dimensions of the rectangular flower garden
can be expressed as:
width = +25+-+2x+ m
length = +35+-+2x+ m
----------------------
She wants to have +324+ square meters of grass
Her whole backyard has an area of +25%2A35+=+875+ m2
--------------
The area of her garden is +875+-+324+=+551+
Now I can say:
+%28+25+-+2x+%29%2A%28+35+-+2x+%29+=+551+
+875+-+70x+-+50x+%2B+4x%5E2+=+551+
+4x%5E2+-+120x+%2B+875+-+551+=+0+
+4x%5E2+-+120x+%2B+324+=+0+
+x%5E2+-+30x+%2B+81+=+0+
+%28+x+-+3+%29%2A%28+x+-+27+%29+=+0+ ( by inspection )
The width of the border can't be +x+=+27+, since
that is wider than her backyard, so
width = +25+-+2%2A3+=+19+ m
length = +35+-+2%2A3+=+29+ m
--------------------------
check answers:
+%28+25+-+2x+%29%2A%28+35+-+2x+%29+=+551+
+%28+25+-+2%2A3+%29%2A%28+35+-+2%2A3+%29+=+551+
+19%2A29+=+551+
+551+=+551+
OK



Miscellaneous_Word_Problems/744333: A train ticket has an area of 192 square centimeter and a perimeter of 56 centimeters. What are the dimensions of the tickets.
1 solutions

Answer 453266 by josmiceli(9685) About Me  on 2013-05-02 15:39:33 (Show Source):
You can put this solution on YOUR website!
+L+ = length in cm
+W+ = width in cm
+A+ = area in cm2
+P+ = perimeter in cm
----------------
(1) +A+=+L%2AW+
(2) +P+=+2L+%2B+2W+
---------------
given:
(1) +192+=+L%2AW+
and
(2) +56+=+2L+%2B+2W+
(2) +L+%2B+W+=+28+
(2) +W+=+28+-+L+
By substitution:
(1) +192+=+L%2A%28+28+-+L+%29+
(1) +L%5E2+-+28L+%2B+192+=+0+
+L+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+
+a+=+1+
+b+=+-28+
+c+=+192+
+L+=+%28-%28-28%29+%2B-+sqrt%28+%28-28%29%5E2+-+4%2A1%2A192+%29%29+%2F+%282%2A1%29+
+L+=+%28+28+%2B-+sqrt%28+784+-+768+%29+%29+%2F+2+
+L+=+%28+28+%2B-+sqrt%28+16+%29+%29+%2F+2+
+L+=+%28+28+-+4+%29+%2F+2+
+L+=+12+
and, also
+L+=+%28+28+%2B+4+%29+%2F+2+
+L+=+16+
-----------
If I pick the larger answer, then
(2) +W+=+28+-+L+
(2) +W+=+28+-+16+
(2) +W+=+12+
---------------
These are the answers, because if I picked +L+=+12+,
then I would get +W+=+16+ for the width
----------
The length is 16 cm
The width is 12 cm




Rate-of-work-word-problems/744074: Billy's pool has a hole and is losing water at a rate of 4/9 gallon per minute. How many hours will it take for Bill to lose 100 gallons?

1 solutions

Answer 453185 by josmiceli(9685) About Me  on 2013-05-01 21:48:50 (Show Source):
You can put this solution on YOUR website!
In terms of units:
( gallons ) / ( gallons / min ) = min
+100+%2F+%28+4%2F9%29+=+%289%2F4%29%2A100+
+%289%2F4%29%2A100+=+225+
This answer is in minutes. To get hours:
( minutes ) x ( hours / minute ) = hours
+225%2A%281%2F60%29+=+3.75+
and +.75%2A60+=+45+
It will take Bill 3 hrs and 45 min


Linear_Equations_And_Systems_Word_Problems/744034: If 900 apples cost me 79 dollars how much would 100 apples cost?
1 solutions

Answer 453155 by josmiceli(9685) About Me  on 2013-05-01 18:48:14 (Show Source):
You can put this solution on YOUR website!
The rate for the apples is
+79+%2F+900+ dollars / apple
In terms of units:
( dollars / apple ) x ( apples ) = dollars
+%28+79%2F900%29%2A100++=+8.78+
100 apples cost $8.78


Equations/744041: can I get the expression and define the variables for this word problem:
The cost of gas is 3.35 per gallon. If you travel 40 miles a day and gas mileage is 25 miles per gallon. How much gas money will be spent in a 5 day work week?
1 solutions

Answer 453153 by josmiceli(9685) About Me  on 2013-05-01 18:42:18 (Show Source):
You can put this solution on YOUR website!
In terms of units:
( dollars / gallon ) x ( ( miles / day ) / ( miles / gallon ) ) x ( days )
After doing the division, you get:
( dollars / gallon ) x ( miles / day ) x ( gallons / mile ) x ( days )
Now I'll do a slight reordering:
( dollars / gallon ) x ( gallons / mile ) x ( miles / day ) x ( days )
Doing the cancellations, I get:
( dollars / mile ) x ( miles ) = dollars
Which is what you're after
Now, plugging in the numbers:
+%28+3.35+%29%2A%28+40+%2F+25+%29%2A5+=+3.35%2A8+
+3.35%2A8+=+26.8+
For a 5 day work week, $26.80 is spent


test/744036: 10zē+3z-3=0 I need to know what is the discriminant? Is it positive or negative? What kind of solution would you get if the discriminant were negative?
Thank You!
1 solutions

Answer 453150 by josmiceli(9685) About Me  on 2013-05-01 18:26:57 (Show Source):
You can put this solution on YOUR website!
When the equation has the form
+ax%5E2+%2B+b%2Ax+%2B+c+ , then the roots are found
using the quadratic formula:
+x+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+
The discriminant is:
+b%5E2+-+4a%2Ac+
If the discriminant is positive, both roots are real
If the discriminant is negative, both roots are imaginary
If the discriminant is zero, there is 1 real root
------------------
Your equation is:
+10z%5E2+%2B+3z+-+3+=+0+
+a+=+10+
+b+=+3+
+c+=+-3+
and the discriminant is:
+b%5E2+-+4%2Aa%2Ac+=+3%5E2+-+4%2A10%2A%28-3%29+
+b%5E2+-+4%2Aa%2Ac+=+9+%2B+120+
+b%5E2+-+4%2Aa%2Ac+=+129+
This result is positive, so there are 2 real roots
Here is the plot:
+graph%28+400%2C+400%2C+-3%2C+3%2C+-5%2C+5%2C+10x%5E2+%2B+3x+-+3+%29+


Rate-of-work-word-problems/744030: one printing machine works twice as fast as another. When both machines are used, they can print a magazine in 3 hrs. How many hours would each machine require to do the job alone?

1 solutions

Answer 453146 by josmiceli(9685) About Me  on 2013-05-01 18:11:12 (Show Source):
You can put this solution on YOUR website!
Add their rates of printing
Let +r+ = the slower machine's rate of printing
+2r+ = the faster machine's rate of printing
When both machines are used, their rate of printing is
( 1 magazine ) / ( 3 hrs )
---------------------
+r+%2B+2r+=+1%2F3+
+3r+=+1%2F3+
+r+=+1%2F9+
+2r+=+2%2F9+
+2r+=+1%2F4.5+
The fast machine can print a magazine in 4.5 hrs
The slow machine can print a magazine in 9 hrs


Percentage-and-ratio-word-problems/743994:
if you have 12 quarters and spend 1/3 of them how much did you spend ? how did you get your answer .
1 solutions

Answer 453127 by josmiceli(9685) About Me  on 2013-05-01 16:54:44 (Show Source):
You can put this solution on YOUR website!
Divide your quarters into 3 piles
( 4 quarters ) + ( 4 quarters ) + ( 4 quarters ) = 12 quarters
You spent one of these piles, which is 4 quarters
+4%2A25+=+100+ cents
+100+ cents = +1+ dollar


Exponential-and-logarithmic-functions/743985: how do you solve log base36(216) without a calculator?
1 solutions

Answer 453125 by josmiceli(9685) About Me  on 2013-05-01 16:51:18 (Show Source):
You can put this solution on YOUR website!
+log%28+36%2C216+%29+
+log%28+36%2C+6%2A36+%29+=+log%28+36%2C6+%29+%2B+log%28+36%2C+36+%29+
+1%2F2+%2B+1+=+3%2F2+ answer
-----------------
To show this is true, I can say
+log%28+36%2C6+%29+%2B+log%28+36%2C+36+%29+=+a+%2B+b+
Now I can say
+36%5Ea+=+6+
+a+=+1%2F2+
and
+36%5Eb+=+36+
+b+=+1+
'OK


Rational-functions/743970: It take one pipe 3 hours to fill the pool and a second pipe 4 hours to drain a pool. The pool is empty and the first pipe begins to fill it. The second pipe is accidentally left open, so the water is also draining out of the pool. Under these conditions how long will it take to fill the pool?
1 solutions

Answer 453120 by josmiceli(9685) About Me  on 2013-05-01 16:39:24 (Show Source):
You can put this solution on YOUR website!
Add the rate of filling and subtract the rate
of draining.
Let +t+ = time in hrs to fill pool with both pipes open
( 1 pool filled ) / ( 3 hrs ) - ( 1 pool emptied ) / ( 4 hrs ) = ( 1 pool filled ) / ( t hrs )
+1%2F3+-+1%2F4+=+1%2Ft+
Multiply both sides by +12t+
+4t+-+3t+=+12+
+t+=+12+
It will take 12 hrs to fill the pool


Travel_Word_Problems/743918: Flying with the wind, a plane traveled 510 miles in 3 hours. Flying against the wind, the plane traveled the same distance in 5 hours. Find the rate of the plane in calm air and the rate of the wind.
1 solutions

Answer 453099 by josmiceli(9685) About Me  on 2013-05-01 15:10:11 (Show Source):
You can put this solution on YOUR website!
Let +p+ = the speed of the plane in still air in mi/hr
Let +w+ = the speed of the wind in mi/hr
+p+%2B+w+ = plane's speed flying with the wind in mi/hr
+p+-+w+ = plane's speed flying against the wind in mi/hr
--------------------
Flying with the wind:
(1) +510+=+%28+p+%2B+w+%29%2A3+
Flying against the wind:
(2) +510+=+%28+p+-+w+%29%2A5+
----------------------
(1) +3p+%2B+3w+=+510+
and
(2) +5p+-+5w+=+510+
---------------------
(1) +p+%2B+w+=+170+
(2) +p+-+w+=+102+
Add the equations
+2p+=+272+
+p+=+136+
and
(1) +136+%2B+w+=+170+
(1) +w+=+34+
The rate of the plane in calm air is 136 mi/hr
The rate of the wind is 34 mi/hr
check:
(2) +136+-+34+=+102+
(2) +102+=+102+
OK




Travel_Word_Problems/743802: The speed of a bayou near Lafayette, Louisiana is 4 miles per hour. A paddle boat travels 48 miles upstream in the same amount of time it takes to travel 72 miles downstream. Find the speed of the boat in still water.
1 solutions

Answer 453074 by josmiceli(9685) About Me  on 2013-05-01 09:52:57 (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed of the boat in still water
+s+%2B+4+ = speed going downstream
+s+-+4+ = speed going upstream
Let +t+ = time for both trips
-------------
Going upstream:
(1) +48+=+%28+s+-+4+%29%2At+
Going downstream:
(2) +72+=+%28+s+%2B+4+%29%2At+
---------------------
This is 2 equations and 2 unknowns, so you
can solve for +s+ and +t+


Equations/743807: What are the values of x and y when (5−3i)−(x+ yi)=(3−i)?
1 solutions

Answer 453072 by josmiceli(9685) About Me  on 2013-05-01 09:45:46 (Show Source):
You can put this solution on YOUR website!
+5+-+3i+-%28+x+%2B+y%2Ai+%29+=+3+-+i+
+5+-+x+-+3i+-+y%2Ai+=+3+-++i+
+%28+5+-+x+%29+-+%28+3+%2B+y+%29%2Ai+=+3+-++i+
----------------------------
I have separated the left side into
a real part and an imaginary part
----------------------------
+5+-+x+=+3+
+-x+=+-2+
+x+=+2+
and
+3+%2B+y+=+1+
+y+=+-2+
----------
check:
+5+-+3i+-%28+x+%2B+y%2Ai+%29+=+3+-+i+
+5+-+3i+-%28+2+%2B+%28-2%29%2Ai+%29+=+3+-+i+
+5+-+3i+-+2+%2B+2i+=+3+-+i+
+3+-+i+=+3+-+i+
OK