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Mixture_Word_Problems/511301: A radiator contains 13 quarts of fluid, 20% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 50% antifreeze? (Round your answer to two decimal places.)

1 solutions

Answer 342148 by josmiceli(9645) About Me  on 2011-10-07 22:48:13 (Show Source):
You can put this solution on YOUR website!
The key is: you start with 13 quarts and you end up with
13 quarts.
Let +x+ = quarts of fluid to be drained
and replaced with pure antifreeze
given:
+.2%2A13+=+2.6+ quarts of original antifreeze
+.2x+ = quarts of antifreeze drained off
-----------------
+%28+2.6+-+.2x+%2B+x+%29+%2F+13+=+.5+
+%28+2.6+%2B+.8x+%29+%2F+13+=+.5+
+2.6+%2B+.8x+=+6.5+
+.8x+=+3.9+
+x+=+4.875+
4.88 quarts of fluid should be drained and replaced with pure antifreeze
check:
+%28+2.6+-+.2x+%2B+x+%29+%2F+13+=+.5+
+%28+2.6+%2B+.8%2A4.875+%29+%2F+13+=+.5+
+%28+2.6+%2B+3.9+%29+%2F+13+=+.5+
+6.5+%2F+13+=+.5+
+6.5+=+6.5+
OK


Equations/511329: This nut bread contains:
3 times as many pecans as Brazil nuts, one more walnut than Brazil nuts, 6 nuts in all

How do I set this problem up? I am in pre algebra and we are simplifying algebraic equations. It is confusing to me.
Thank you!
1 solutions

Answer 342137 by josmiceli(9645) About Me  on 2011-10-07 22:19:53 (Show Source):
You can put this solution on YOUR website!
You can say
Let +p+ = number of pecans
Let +b+ = number of Brazil nuts
Let +w+ = number of walnuts
given:
(1) +p+=+3b+
(2) +w+=+b+%2B+1+
(3) +p+%2B+b+%2B+w+=+6+
----------------
There are 3 equations and 3 unknowns, so
this is solvable.
It's not easy going from the words to the equation.
I still get confused sometimes, so keep working at it.


Radicals/511315: On a map 1 1/2 inches represents 315 miles, the distance between two major cities measure 2 3/4 inches apart(as the crow flies), how far would this be on the earths surface.Let m represent the number of miles between the two cities.
1 solutions

Answer 342132 by josmiceli(9645) About Me  on 2011-10-07 22:10:49 (Show Source):
You can put this solution on YOUR website!
You can make a ratio
+1.5+%2F+2.75+=+315+%2F+m+
+1.5m+=+2.75%2A315+
+1.5m+=+866.25+
+m+=+577.5+
The cities are 577.5 mi apart


percentage/511318: i have 21 students surveyed to see how many participated in specifics sports. I need a circle or pie graph to show results.
9 kids play soccer, 1 play baseball, 5 play basktball, 4 play football, 2 play tennis. How do i know the percentage of the class who play each sport?
1 solutions

Answer 342127 by josmiceli(9645) About Me  on 2011-10-07 22:04:17 (Show Source):
You can put this solution on YOUR website!
Express each sport as a fraction
+9%2F21+ of +21+ students play soccer
+1%2F21+ of +21+ students play baseball
etc.
There are +360+ degrees in a circle, so find
what part of a circle each fraction represents
+%289%2F21%29%2A360+=+154.286+ degrees
+%281%2F21%29%2A360+=+17.143+ degrees
+%285%2F21%29%2A360+=+85.714+ degrees
etc.
If you add up all the slices of the pie,
you should get 360 degrees


Mixture_Word_Problems/511311: how many milliliters of water must be added to 250 ml of 25% salt solution to reduce the concentration to 10%
1 solutions

Answer 342118 by josmiceli(9645) About Me  on 2011-10-07 21:52:22 (Show Source):
You can put this solution on YOUR website!
Let w = ml of water to be added
given:
+.25%2A250+=+62.5+ ml of salt in 25% solution
+62.5+%2F+%28+250+%2B+x+%29+=+.1+
+62.5+=+.1%2A%28+250+%2B+x+%29+
+62.5++=+25+%2B+.1x+
+.1x+=+62.5+-+25+
+.1x+=+37.5+
+x+=+375+
375 ml of water must be added


Equations/511308: Please help me solve this equation:
Find the equation of the line perpendicular to -3x+7y=-3 that contains the point (7,6)
1 solutions

Answer 342107 by josmiceli(9645) About Me  on 2011-10-07 20:53:05 (Show Source):
You can put this solution on YOUR website!
First, find the slope of +-3x+%2B+7y+=+-3+
Get it into the form +y+=+mx+%2B+b+ where m
is the slope.
+7y+=+3x+-+3+
+y+=+%283%2F7%29%2Ax+-+3+
Any line perpendicular to this line will have
slope = +-1%2Fm+
+m+=+3%2F7+
+-1%2Fm+=+-7%2F3+
Now use the point-slope formula to find the line
that includes (7,6) and has slope - 7/3
+%28+y+-+6+%29+%2F+%28+x+-+7+%29+=+-7%2F3+
+y+-+6+=+-%287%2F3%29%2A%28+x+-+7+%29+
+3%2A%28+y+-+6+%29+=+-7x+%2B+49+
+3y+-+18+=+-7x+%2B+49+
+7x+%2B+3y+=+67+ answer
check:
does it contain (7,6)?
+7%2A7+%2B+3%2A6+=+67+
+49+%2B+18+=+67+
+67+=+67+
OK


Money_Word_Problems/511299: You have already invested $350 in a stock with an annual return of 11%. How much of an additional $800 should be invested at 12% and how much at 6% so that the total return on the entire $1,150 is 9%? (Round each answer to the nearest cent.)

1 solutions

Answer 342104 by josmiceli(9645) About Me  on 2011-10-07 20:41:29 (Show Source):
You can put this solution on YOUR website!
Let a = amount invested @ 12%
Let b = amount invested @ 6%
given:
++.11%2A350+=+38.5 is Return on $350 @ 11%
+.09%2A1150+=103.5+ is return on $1150 @ 9%
--------------
(1) +a+%2B+b+=+800+
(2) +38.5+%2B+.12a+%2B+.06b+=+103.5+
------------------------
Multiply both sides of (2) by 100
(2) +3850+%2B+12a+%2B+6b+=+10350+
(2) +12a+%2B+6b+=+6500+
(2) +6a+%2B+3b+=+3250+
Multiply both sides of (1) by +3+ and
subtract (1) from (2)
(2) +6a+%2B+3b+=+3250+
(1) +-3a+-+3b+=+-2400+
+3a+=+850+
+a+=+283.33+
and, since
+a+%2B+b+=+800+
+b+=+800+-+283.33+
+b+=+516.67+
$283.33 should be invested @ 12% and
$516.67 should be invested @ 6%
check:
(2) +38.5+%2B+.12%2A283.33+%2B+.06%2A516.67+=+103.5+
(2) +38.5+%2B+34+%2B+31+=+103.5+
(2) +103.5+=+103.5+
OK


Mixture_Word_Problems/511241: A radiator contains 9 quarts of fluid, 40% of which is antifreeze. How much fluid should be drained and replaced with pure antifreeze so that the new mixture is 55% antifreeze?
1 solutions

Answer 342083 by josmiceli(9645) About Me  on 2011-10-07 17:53:58 (Show Source):
You can put this solution on YOUR website!
In words:
( final quarts of antifreeze) / ( final quarts of fluid ) = 55%
Let +x+ = quarts of fluid to be drained
and replaced with pure antifreeze
given:
+.4%2A9+=+3.6+ = quarts of antifreeze in original mixture
+.4x+ = quarts of antifreeze that is drained off
------------
+%28+3.6+-+.4x+%2B+x+%29+%2F+9+=+.55+
+%28+3.6+%2B+.6x+%29+%2F+9+=+.55+
+3.6+%2B+.6x+=+4.95+
+.6x+=+4.95+-+3.6+
+.6x+=+1.35+
+x+=+2.25+
2.25 quarts of fluid should be drained
and replaced with pure antifreeze
check:
+%28+3.6+%2B+.6%2A2.25+%29+%2F+9+=+.55+
+%28+3.6+%2B+1.35+%29+%2F+9+=+.55+
+4.95+%2F+9+=+.55+
+4.95+=+4.95+
OK


Polynomials-and-rational-expressions/510533: Simplify the eepression: (8x^6y^9)^(2/3)/(16x^8y^-4)^(1/2)
I don't know weather to work this like a polynomial and divide. My problem just seems to get longer than shorter. Thank you so much for your help.

1 solutions

Answer 341831 by josmiceli(9645) About Me  on 2011-10-06 11:23:38 (Show Source):
You can put this solution on YOUR website!
You can use the rules for exponents:
+%28a%5Eb%29%5Ec+=+a%5E%28b%2Ac%29+
+%28a%2Ab%29%5Ec+=+a%5Ec%2Ab%5Ec+
-------------------
+%288x%5E6%2Ay%5E9%29%5E%282%2F3%29%2F%2816%2Ax%5E8%2Ay%5E%28-4%29%29%5E%281%2F2%29+
(note that +8+=+2%5E3+ and +16+=+4%5E2+ )
( and +%282%5E3%29%5E%282%2F3%29+=+4+ and +%284%5E2%29%5E%281%2F2%29+=+4+ )
+%284x%5E4%2Ay%5E6%29+%2F+%284x%5E4%2Ay%5E%28-2%29%29+
+%28%284x%5E4%29+%2F+%284x%5E4%29%29%2A%28%28y%5E6%29+%2F+%28y%5E%28-2%29%29%29+
+y%5E6%2Ay%5E2+
+y%5E8+
Unless I made a mistake- I would get another opinion, too


Age_Word_Problems/510514: Zoron is ten years older than his sister. In three years, he will be twice as old as she will be then. How old are they now?
1 solutions

Answer 341828 by josmiceli(9645) About Me  on 2011-10-06 10:17:06 (Show Source):
You can put this solution on YOUR website!
Let z = Zoron's age now
Let s = his sister's age now
given:
+z+=+s+%2B+10+
+z+%2B+3++=+2%2A%28+s+%2B+3+%29+
-------------------
By substitution:
+s+%2B+10+%2B+3++=+2%2A%28+s+%2B+3+%29+
+s+%2B+13+=+2s+%2B+6+
+s+=+13+-+6+
+s+=+7+
and
+z+=+s+%2B+10+
+z+=+17+
Zoron is 17 and his sister is 7
check:
In 3 years, he will be 20 and she will be 10
OK


Word_Problems_With_Coins/510170: A parking meter costs .50 for one hour. it takes quarters dimes and nickles how many different combinations are there to equal .50
I came up with an answer of 1901 was I close or way off
thank you for your help
Alexis 7th grade
1 solutions

Answer 341741 by josmiceli(9645) About Me  on 2011-10-05 18:46:16 (Show Source):
You can put this solution on YOUR website!
d - n - q
--------
5
4 - 2
3 - 4
2 - 6
1 - 8
0 - 10
2 - 1 - 1
1 - 3 - 1
0 - 5 - 1
0 - 0 - 2
---------
10
There are 10 ways to make 50 cents
using nickels, dimes, and quarters


Money_Word_Problems/510063: Mr. Jamison buys a washing machine that is listed at $800. It is advertised at a 20% discount. At the store, he receives an additional 10% off the sale price, but he discovers that he must pay 6% sales tax on the reduced price of the machine plus a $40 delivery charge.
- I have to write an equation that would represent the final cost of the machine. Thanks!
1 solutions

Answer 341692 by josmiceli(9645) About Me  on 2011-10-05 16:46:50 (Show Source):
You can put this solution on YOUR website!
Call the list price p
Given: ++p+=+800+
I think the equation would be:
+%28+p+-+.2p%29%2A%28+1+-+.1+%29+%2A%28+1+%2B+.06+%29+%2B+40+
+p%2A.8%2A.9%2A1.06+%2B+40+
cost of machine = +.7632p+%2B+40+
Just plug in +p+=+800+ to solve


Rate-of-work-word-problems/509741: if 10 men take 3 day to complete a piece of work.how may days will 2 men take to complete the same work?
1 solutions

Answer 341579 by josmiceli(9645) About Me  on 2011-10-04 23:57:38 (Show Source):
You can put this solution on YOUR website!
10 men take 3 days
1 man will take 10 times as long to finish, or
30 days
2 men will take half of that time, or 15 days


test/509686: 3 chickens and a duck sold for as much as 2 geese;1chicken, 2 ducks, and 3 geese were sold for $25.00. What was the price of each bird in exact number of dollars?
1 solutions

Answer 341578 by josmiceli(9645) About Me  on 2011-10-04 23:48:50 (Show Source):
You can put this solution on YOUR website!
(1) +3c+%2B+d+=+2g+
(2) +c+%2B+2d+%2B+3g+=+25+
---------------------
(1) +3c+%2B+d+-+2g+=+0+
(2) +c+%2B+2d+%2B+3g+=+25+
Add the equations:
(3) +4c+%2B+3d+%2B+g+=+25+
---------------------
There are 3 unknowns and only 2 equations, so it isn't
directly solvable, but trial and error might work
Suppose
g = 6
d = 1
c = 4
Almost
(2) +24+=+25+
(3) +25+=+25+
Suppose
g = 5
d = 4
c = 2
I think this works!
(1) +3c+%2B+d+=+2g+
(1) +3%2A2+%2B+4+=+2%2A5+
(1) +6+%2B+4+=+10+
(1) +10+=+10+
OK
(2) +c+%2B+2d+%2B+3g+=+25+
(2) +2+%2B+2%2A4+%2B+3%2A5+=+25+
(2) +2+%2B+8+%2B+15+=+25+
(2) +25+=+25+
OK
Ducks cost $4 ea
Chickens cost $2 ea
Geese cost $5 ea


Expressions-with-variables/509721: I am struggling in the set up of this problem. Can you please help me?
The current in a bayou near Lafayette is 4 miles per hour. A paddleboat travels 48 miles up stream 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 341574 by josmiceli(9645) About Me  on 2011-10-04 23:13:05 (Show Source):
You can put this solution on YOUR website!
Let s = speed of boat in still water
Let t = time it takes to go either upstream or downstream
+c+=+4+ is the speed of the current
+s+%2B+c+ is the boat's speed going downstream
+s+-+c+ is the boat's speed going upstream
------------
given:
Going upstream:
(1) +48+=+%28s+-+4%29%2At+
Going downstream:
(2) +72+=+%28s+%2B+4%29%2At+
-------------------
(1) +48+=+s%2At+-+4t+
and
(2) +72+=+s%2At+%2B+4t+
Subtract (1) from (2)
(2) +72+=+s%2At+%2B+4t+
(1) +-48+=+-s%2At+%2B+4t+
+24+=+8t+
+t+=+3+
By substitution:
(1) +48+=+%28s+-+4%29%2A3+
(1) +48+=+3s+-+12+
(1) +3s+=+60+
(1) +s+=+20+
The speed in still water is 20 mi/hr
check answer:
(2) +72+=+%2820+%2B+4%29%2A3+
(2) +72+=+24%2A3+
(2) +72+=+72+
OK


test/509715: How Could You Change The Pitch of A Roof To Make It Steeper Using Rise And Run?
1 solutions

Answer 341566 by josmiceli(9645) About Me  on 2011-10-04 23:00:24 (Show Source):
You can put this solution on YOUR website!
pitch = rise/run
The roof gets steeper when
rise becomes greater than run,
so increasing rise makes it steeper
Also decreasing the run makes it steeper


Age_Word_Problems/509698: rea is 5 years older than jen-jen. in 4 years, rea will be twice as old as jen-jen. how old is each.
1 solutions

Answer 341565 by josmiceli(9645) About Me  on 2011-10-04 22:57:37 (Show Source):
You can put this solution on YOUR website!
Let r = Rea's age now
Let j = Jen-Jen's age now
given:
+r+=+j+%2B+5+
+r+%2B+4+=+2%2A%28j+%2B+4%29+
By substitution:
+j+%2B+5+%2B+4+=+2%2A%28j+%2B+4%29+
+j+%2B+9+=+2j+%2B+8+
+j+=+1+
and
+r+=+j+%2B+5+
+r+=+6+
Jen-Jen is 1
Rea is 6


Age_Word_Problems/509695: Amy is 7 years older than Tom while Tom is twice as old as Jill. Chris is 3 times as old as Amy. If the sum of Chris and Amy's age is 68. Find Toms age.

Please help. i have the answer but my equation is wrong...
1 solutions

Answer 341559 by josmiceli(9645) About Me  on 2011-10-04 22:46:21 (Show Source):
You can put this solution on YOUR website!
Let a = Amy's age
Let t = Tom's age
Let j = Jill's age
Let c = Chris's age
----------------------
given:
(1) +a+=+t+%2B+7+
(2) +t+=+2j+
(3) +c+=+3a+
(4) +c+%2B+a+=+68+
--------------
There are 4 unknowns and 4 equations
so this should be solvable
Substitute (3) into (4)
(4) +c+%2B+a+=+68+
(4) +3a+%2B+a+=+68+
(4) +4a+=+68+
(4) +a+=+17+
Substitute this result into (1)
(1) +a+=+t+%2B+7+
(1) +17+=+t+%2B+7+
(1) +t+=+17+-+7+
(1) +t+=+10+
Substitute this result into (2)
(2) +t+=+2j+
(2) +10+=+2j+
(2) +j+=+5+
and, also
(3) +c+=+3a+
(3) +c+=+3%2A17+
(3) +c+=+51+
----------------
Amy's age is 17
Tom's age is 10
Jill's age is 5
Chris's age is 51


Expressions-with-variables/509700: Will you please help me solve for a: 15a-2(4a+5)=-6a
1 solutions

Answer 341553 by josmiceli(9645) About Me  on 2011-10-04 22:31:57 (Show Source):
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+15a-2%284a%2B5%29=-6a+
+15a+-+8a+-+10+=+-6a+
Add 6a to both sides
+15a+-+8a+%2B+6a+-+10+=+0+
Add 10 to both sides
+15a+-+8a+%2B+6a+=+10+
Do the indicated addition and
subtraction of terms on the left side
+13a+=+10+
+a+=+10%2F13+
--------------
You can check this by putting
answer back into original equation
I'll use decimal equivilant +10%2F13+=+.7692+
+15a-2%284a%2B5%29=-6a+
+15%2A.7692-2%284%2A.7692%2B5%29=-6%2A.7692+
+11.5385+-+2%2A%283.0768+%2B+5%29+=+-4.6152+
+11.5385+-+2%2A8.0768+=+-4.6152+
+11.5385+-+16.1536+=+-4.6152+
+-4.6151+=+-4.6152+
OK- the error must be due to rounding off


Angles/509696: one of two complementary angles has a measure that is six more than twice the others. find the measure of the larger angle
1 solutions

Answer 341547 by josmiceli(9645) About Me  on 2011-10-04 22:19:06 (Show Source):
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Call the angles A and B in degrees
given:
+A+=+2B+%2B+6+%7D%7D%0D%0A-------------%0D%0A%7B%7B%7B+A+%2B+B+=+90+
+B+=+90+-+A+
and
+A+=+2%2A%2890+-+A%29+%2B+6+
+A+=+180+-+2A+%2B+6+
+3A+=+186+
+A+=+62+
+B+=+90+-+62+
+B+=+28+
The larger angle is 62 degrees


Mixture_Word_Problems/509429: How much sand must be added to 250 kg of a cement mixture that is 22% sand to have a mixture that is 25% sand?
1 solutions

Answer 341456 by josmiceli(9645) About Me  on 2011-10-04 18:25:28 (Show Source):
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Let x = kg of cement to be added
given:
+.22%2A250+=+55+ kg of sand initially
----------
+%28x+%2B+55%29+%2F+%28x+%2B+250%29+=+.25+
+x+%2B+55+=+.25%2A%28x+%2B+250%29+
+x+%2B+55+=+.25x+%2B+62.5+
+.75x+=+7.5+
+x+=+10+
10 kg of sand must be added
check:
+%28x+%2B+55%29+%2F+%28x+%2B+250%29+=+.25+
+%2810+%2B+55%29+%2F+%2810+%2B+250%29+=+.25+
+65+%2F+260+=+.25+
+65+=+65+
OK


Exponents/509418: What does 7.8903^10 to the negative one equals

What does 4.4296^10 to the third power equals

What does 1^10 to the negative fourth power equals
1 solutions

Answer 341448 by josmiceli(9645) About Me  on 2011-10-04 18:15:33 (Show Source):
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the general rule to follow is:
+%28a%5Eb%29%5Ec+=+a%5E%28b%2Ac%29+
-----------
+%287.8903%5E10%29%5E%28-1%29+
+7.8903%5E%28-10%29+
+1+%2F+7.8903%5E10+
Use calculator
--------------
+%284.4296%5E10%29%5E3+
+4.4296%5E30+
Use calculator
--------------
+%28+1%5E10%29%5E%28-4%29+
+1%5E%28-40%29+
+1+%2F+%281%5E40%29+
+1+


Travel_Word_Problems/509378: The Cuyahoga river has current of 2 mph. Two boats start downstream at the same time with one boat 5 miles faster in still water than the other one. How long will it take for the boats to be 25 miles apart if the slower boat can travel 12 miles upstream in 2 hours?
1 solutions

Answer 341427 by josmiceli(9645) About Me  on 2011-10-04 17:46:33 (Show Source):
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Let +t+ = time for the boats to be +25+%7D%7D+mi+apart%0D%0Agiven%3A%0D%0A%7B%7B%7B+c+=+2+ mi/hr is the current
+s+ mi/hr = speed of slower boat in still water
+s+%2B+5+ mi/hr = speed of faster boat in still water
The slower boat going upstream:
+12+=+%28+s+-+2+%29%2A2+
+12+=+2s+-+4+
+2s+=+16+
+s+=+8+ mi/hr
---------------
Going downstream:
slower boat:
+d+=+%28+8+%2B+2%29%2At+
(1) +d+=+10t+
faster boat:
+d+%2B+25+=+%28+8+%2B+5+%2B+2+%29%2At+
(2) +d+%2B+25+=+15t+
Substitute (1) into (2)
(2) +10t+%2B+25+=+15t+
(2) +5t+=+25+
(2) +t+=+5+
In 5 hrs, the boats will be 25 mi apart
check answer:
(1) +d+=+10%2A5+
(1) +d+=+50+ mi
and
(2) +d+%2B+25+=+15t+
(2) +75+=+15t+
(2) +t+=+5+
OK


Equations/509189: Please help me solve.
Tom, Dave, and Harry went crabbin'. Dave caught 5 more crabs then Tom. Harry caught twice the number Dave caught. They ended the day with 75 crabs. How many crabs did each catch?
1 solutions

Answer 341355 by josmiceli(9645) About Me  on 2011-10-04 14:16:07 (Show Source):
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Tom, Dave, and Harry caught t,d, and h
number of crabs
given:
(1) +d+=+t+%2B+5+
(2) +h+=+2d+
(3) +t+%2B+d+%2B+h+=+75+
----------------
(1) +t+=+d+-+5+
Substitute (1) and (2) into (3)
(3) +d+-+5+%2B+d+%2B+2d+=+75+
(3) +4d+=+80+
(3) +d+=+20+
and
(2) +h+=+2%2A20+
(2) +h+=+40+
and
(1) +t+=+20+-+5+
(1) +t+=+15+
Tom, Dave, and Harry caught 15, 20, and 40 crabs


Travel_Word_Problems/509241: A private plan leaves an airport and flies due east at 192 miles per hour. Two hours later, a jet leaves the same airport and flies due east at 960 miles per hour. How far will the private plan fly before it is passed by the jet?
1 solutions

Answer 341354 by josmiceli(9645) About Me  on 2011-10-04 14:03:36 (Show Source):
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How much of a head start does the private plane get?
+d%5B1%5D+=+192%2A2+
+d%5B1%5D+=+384+ mi
---------------
Now start a stopwatch when the jet leaves
For the jet:
(1) +d+=+960t+
For the private plane:
(2) +d+-+384+=+192t+
( Note that t is the same for both,
since they are both on the stopwatch now )
---------------
Substitute (1) into (2)
+960t+-+384+=+192t+
+768t+=+384+
+t+=+.5+ hrs
The private plane is passed by the jet in 1/2 hr


Rectangles/509236: The length of a rectangle is five times its width.
If the area of the rectangle is 320cm^2 , find its perimeter




1 solutions

Answer 341349 by josmiceli(9645) About Me  on 2011-10-04 13:52:32 (Show Source):
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The formula for perimeter is:
+P+=+2W+%2B+2L+
The formula for area is:
+A+=+L%2AW+
given:
+A+=+320+ cm2
(1)+L+=+5W+
----------
(2) +320+=+L%2AW+
(2) +L+=+320%2FW+
Substitute (2) into (1)
+320%2FW+=+5W+
+320+=+5W%5E2+
+W%5E2+=+64+
+W+=+8+
and, since
+L+=+5W+
+L+=+40+
The length is 40 cm and the width is 8 cm
so, the perimeter is
+P+=+2W+%2B+2L+
+P+=+2%2A8+%2B+2%2A40+
+P+=+16+%2B+80+
+P+=+96+ cm


Evaluation_Word_Problems/509208: Find the slope (m) of a line that passes through the following points.
(m = - 1/7) (4, 2), (-3, 1)
1 solutions

Answer 341331 by josmiceli(9645) About Me  on 2011-10-04 12:44:50 (Show Source):
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I get +1%2F7+ for the slope
slope = ( change in y ) / ( change in x )
+%282+-+1%29+%2F+%284+-%28-3%29%29+=+1%2F7+


Travel_Word_Problems/508978: Flying with a tailwind a jet can fly 2520 miles in 4 hours. Flying against the same wind, it covers 1720 miles in the same amount of time. Determine the speed of the jet in calm air.
1 solutions

Answer 341216 by josmiceli(9645) About Me  on 2011-10-03 22:28:27 (Show Source):
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Let p = speed of the jet in calm air
Let w = speed of wind
given:
(1) +p+%2B+w+=+2520%2F4+
(2) +p+-+w+=+1720%2F4+
-------------------
(1) +p+%2B+w+=+630+
(2) +p+-+w+=+430+
Add the equations
+2p+=+1060+
+p+=+530+
and, since
(2) +p+-+w+=+430+
(2) +530+-+w+=+430+
(2) +w+=+530+-+430+
(2) +w+=+100+
The speed of the jet in calm air is 530 mi/hr


test/508955: it is between 50 000 and 52 000.
there is a 2 in the tens place.
the sum of the digits is 23

1 solutions

Answer 341213 by josmiceli(9645) About Me  on 2011-10-03 22:13:55 (Show Source):
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The ten-thousands digit is 5
The thousands digit is either 0 or 1
The tens digit is 2
So far, I have either
50a2b or
51a2b
In the 1st case, +5+%2B+0+%2B+a+%2B+2+%2B+b+=+23+
+a+%2B+b+=+16+
In the 2nd case, +5+%2B+1+%2B+a+%2B+2+%2B+b+=+23+
+a+%2B+b+=+17+
What's the question?
There are lots of possible answers


Permutations/508959: How many different 4-letter radio call letters can be made using the 26 capital letters of the English alphabet (Examples: WJBR, KDKA, WSTW) if the first letter must be K or W and no letter may be repeated.
1 solutions

Answer 341191 by josmiceli(9645) About Me  on 2011-10-03 21:32:16 (Show Source):
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There are 2 possible choices for the 1st letter
Repetitions are not allowed, so
there are +25+ choices for the 2nd letter
+24+ for the 3rd letter
+23+ for the 4th letter
Multiply possible choices to get all
possible combinations of letters
+2%2A25%2A24%2A23+=+27600+
There are 27600 possible 4-letter radio call signs



Mixture_Word_Problems/508940: I have a 70% meat and30% meat need to get 37% but it has to weigh 3060pounds
1 solutions

Answer 341182 by josmiceli(9645) About Me  on 2011-10-03 21:24:25 (Show Source):
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Let a = pounds of 70% meat needed
Let b = pounds of 30% meat needed
given:
(1) +a+%2B+b+=+3060+ pounds
(2) +%28.7a+%2B+.3b%29+%2F+3060+=+.37+
--------------------------
(2) +.7a+%2B+.3b+=+1132.2+
(2) +7a+%2B+3b+=+11322+
Multiply both sides of (1) by +3+
and subtract (1) from (2)
(2) +7a+%2B+3b+=+11322+
(1) +-3a+-+3b+=+-9180+
+4a+=+2142+
+a+=+535.5+
and, since
(1) +a+%2B+b+=+3060+
(1) +b+=+3060+-+535.5+
(1) +b+=+2524.5+
535.5 pounds of 70% meat are needed
2524.5 pounds of 30% meat are needed
check answer:
(2) +%28.7a+%2B+.3b%29+%2F+3060+=+.37+
(2) +%28.7%2A535.5+%2B+.3%2A2524.5%29+%2F+3060+=+.37+
(2) +%28374.85+%2B+757.35%29+%2F+3060+=+.37+
(2) +1132.2+%2F+3060+=+.37+
(2) +1132.2+=+1132.2+
OK