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josmiceli answered: 9658 problems
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Money_Word_Problems/221223: how many tons of hay at $125 per ton and $75 per ton must be purchased to have 100 tons of hay worth $9000?
1 solutions

Answer 165990 by josmiceli(9661) About Me  on 2009-10-04 01:21:56 (Show Source):
You can put this solution on YOUR website!
Let a = tons of $125/ton hay used
Let b = tons of $75/ton hay used
given:
(1) a+%2B+b+=+100
(2) 125a+%2B+75b+=+9000
---------------------------
Multiply both sides of (1) by 75 and
subtract from (2)
(2) 125a+%2B+75b+=+9000
(1) -75a+%2B+-75b+=+-7500
50a+=+1500
a+=+30
and, since
a+%2B+b+=+100
30+%2B+b+=+100
b+=+70
30 tons of $125/ton hay and 70 tons of $75/ton hay
must be purchased
check:
(2) 125a+%2B+75b+=+9000
125%2A30+%2B+75%2A70+=+9000
3750+%2B+5250+=+9000
9000+=+9000
OK



Linear-equations/221111: x=number of white paint can
y=number of blue paints can
x=y=5 cans of paint
white paint = $ 24
blue paint = $ 28
24x + 28y = $132
How do you solve: 24x + 28y = 132 ?
How steps.
1 solutions

Answer 165891 by josmiceli(9661) About Me  on 2009-10-03 17:24:19 (Show Source):
You can put this solution on YOUR website!
You can't solve it. There are 2 variables, x and y,
so you need 2 equations to solve.
You wrote
x=y=5. I think you mistyped & actually
meant x+%2B+y+=+5
That's your other equation
Multiply both sides of this equation by 24
24x+%2B+24y+=+120
Now subtract it from the other equation
24x+%2B+28y+=+132
-24x+-+24y+=+-120
4y+=+12
y+=+3
and, since x+%2B+y+=+5
x+=+2
Hope this helps


Permutations/220982: A single die is rolled twice. Find the probability of rolling an odd number the first time and a number less than 3 the second time.
thank you for your help!
1 solutions

Answer 165777 by josmiceli(9661) About Me  on 2009-10-03 11:44:02 (Show Source):
You can put this solution on YOUR website!
The 6 sides of the die are numbered 1,2,3,4,5,6
There are 3 odd and 3 even numbers
probability of an odd number on 1st roll is
3%2F6+=+1%2F2
When you want A AND B probabilities, you multiply
the events A and B
The number less than 3 are 1,2, so the probability is
2%2F6+=+1%2F3
And the probability of getting both these events is
%281%2F2%29+%2A+%281%2F3%29+=+1%2F6


Quadratic_Equations/220887: I don't understand how to use the formula of ax^+bx+c=0
My problem is this x^2+7x=180
I need x answered
1 solutions

Answer 165739 by josmiceli(9661) About Me  on 2009-10-03 01:07:38 (Show Source):
You can put this solution on YOUR website!
The equation is called quadratic, or 2nd degree.
When you plot it on a graph, it's called a parabola.
It's in the form ax%5E2+%2B+bx+%2B+c+=+0, but first
subtract 180 from both sides, and it will be in
that form
x%5E2+%2B+7x+-+180+=+0
Matching it up with the general equation,
a+=+1
b+=+7
c+=+-180
Now use the quadratic formula to solve
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-7+%2B-+sqrt%28+7%5E2-4%2A1%2A%28-180%29+%29%29%2F%282%2A1%29+
x+=+%28-7+%2B-+sqrt%28+49+%2B+720+%29%29%2F%282%2A1%29+
x+=+%28-7+%2B-+sqrt%28+769+%29%29%2F2+
769 isn't a perfect square- are you sure you
copied this right?


Miscellaneous_Word_Problems/220907: When the Johnson triplets were three weeks old, their sleep habits were remarkably consistent. John slept for 3 hours and was awake for 30 minutes. Joan slept for 2 hours and was awake for 30 minutes. Jane slept for 2 hours 20 minutes and was awake for 40 minutes. On October 13 at 8:00 P.M., they all went to sleep at the same time. When did this event occur again? Give both the date and time.

1 solutions

Answer 165737 by josmiceli(9661) About Me  on 2009-10-03 00:55:49 (Show Source):
You can put this solution on YOUR website!
Each one has a different sleep-awake cycle:
John's is
3+%2B+1%2F2 hrs
Joan's is
2+%2B+1%2F2 hrs
Jane's is
2+%2B+1%2F3+%2B+2%2F3+=+3 hrs
Call the lengths of these cycles a,b, and c
Now I can say
2a+=+7
2b+=+5
2c+=+6
Note that 7%2A5%2A6+=+210, and
2a+=+210%2F30
2b+=+210%2F42
2c+=+210%2F35
Finally, I can say
60a+=+210
84b+=+210
70c+=+210
60 sleep-awake cycles for John, 84 sleep-awake cycles for Joan
and 70 sleep-awake cycles for Jane all end together 210 hours
from Oct 13, 8 PM
210%2F24+=+8.75 days
and
.75%2A24+=+18 hours
8 days would make it Oct 21, 8 PM
Adding 18 hours makes it
Oct 22, 2 PM they all go to sleep again at the same time
check answer
For John:
60%2A3.5+=+210
84%2A2.5+=+210
70%2A3+=+210
OK


Exponential-and-logarithmic-functions/220853: Dear Tutor,
Please help me solve this tedious math problem. Your help is GREATLY appreciated. Thanks so much!!! :)

By the way, I need to solve by factoring the square
4x^2-4x-99=0
1 solutions

Answer 165726 by josmiceli(9661) About Me  on 2009-10-03 00:19:22 (Show Source):
You can put this solution on YOUR website!
4x%5E2+-+4x+-+99+=+0
First divide both sides by 4
x%5E2+-+x+-+99%2F4+=+0
Now add 99%2F4 to both sides
x%5E2+-+x+=+99%2F4
Now take 1/2 of the coefficient of x
which is -1, square it, and add it to
both sides
x%5E2+-+x+%2B+%28-1%2F2%29%5E2+=+99%2F4+%2B+%28-1%2F2%29%5E2
x%5E2+-+x+%2B+1%2F4+=+99%2F4+%2B+1%2F4
x%5E2+-+x+%2B+1%2F4+=+100%2F4
Notice that both sides are perfect squares
%28x+-+1%2F2%29%5E2+=+%2810%2F2%29%5E2
I'll take the square root of both sides
x+-+1%2F2+=+10%2F2
x+=+10%2F2+%2B+1%2F2
x+=+11%2F2
There is also a negative square root
x+-+1%2F2+=+-10%2F2
x+=+-9%2F2
The roots are x+=+11%2F2 and x+=+-9%2F2
I'll plot it to verify
+graph%28+600%2C+600%2C+-10%2C+10%2C+-110%2C+5%2C+4x%5E2+-+4x+-+99%29+
Looks about right


Exponents-negative-and-fractional/220863: i don't get negative numbers please explain
1 solutions

Answer 165689 by josmiceli(9661) About Me  on 2009-10-02 19:46:10 (Show Source):
You can put this solution on YOUR website!
Sometime a negative number seems like a ghost
and sometimes it's clearly visible.
It depends on what you're using them for.
(A)
Let's say I'm on a railroad track that runs east and west.
If I want to, I can say that if I go west, that's positive
motion, and if I go east, that's negative motion.
OK, I go W 1 mile, I go E 2 miles, then I go W 6 miles.
How far am I from where I started?
I went W +1 miles
I went E -2 miles
I went W +6 miles
1 - 2 + 6 = +5 miles
I am 5 miles west of where I started.
(B)
Let's say I owe you $5. I've got the $5, so
it's a (+) on my records until it's spent.
You're missing the $5, so it's a (-) on your
records until I pay it back.
What does -$5 look like? Nobody's ever seen one,
but recordkeeping can't work without it.
Think of it as an empty pocket that only holds
a single $5 bill, and you're always reminded
that it's empty and needs to be filled.
It's the -$5 pocket.
Does that help at all? You need to keep
thinking about it.


Systems-of-equations/220821: this is a word problem i cant figure it out please help: one canned juice drink is 20% orange juice, another os 10% orange juice. How many liters pf each should be mixed togethre in order to get 10L that is 12% orange juice?
1 solutions

Answer 165686 by josmiceli(9661) About Me  on 2009-10-02 19:24:06 (Show Source):
You can put this solution on YOUR website!
Let a = liters of 20% juice needed
Let b = liters of 10% juice needed
given:
(1) a+%2B+b+=+10 liters of 12% mixture
OJ in 20% juice is .2a liters
OJ in 10% juice is .1b liters
OJ in 12% juice is .12%2A10+=+1.2 liters
In words:
(liters OJ in 20% mix + liters OJ in 10% mix)/(total liters of 12% mix) = 12%
%28.2a+%2B+.1b%29%2F10+=+.12
.2a+%2B+.1b+=+1.2
(2) 2a+%2B+b+=+12
Subtract (1) from (2)
(2) 2a+%2B+b+=+12
(1) -a+-+b+=+-10
a+=+2 liters
and, since
a+%2B+b+=+10
2+%2B+b+=+10
b+=+8 liters
2 liters of the 20% juice and 8 liters of the 10%
juice need to be mixed
check answer:
%28.2a+%2B+.1b%29%2F10+=+.12
%28.2%2A2+%2B+.1%2A8%29%2F10+=+.12
%28.4+%2B+.8%29%2F10+=+.12
1.2%2F10+=+.12
1.2+=+1.2
OK



Miscellaneous_Word_Problems/220828: I'm taking algebra but I have a hard time with word problems. Please help.
1) A certain granola mixture is 10% peanuts.
A) If a container has 20 lbs. of granola how many pounds of peanuts does it contain?
B) If a container has X lbs. of granola in it write an expression for the amount of peanuts it contains.

Thank you for any help!

1 solutions

Answer 165681 by josmiceli(9661) About Me  on 2009-10-02 17:59:41 (Show Source):
You can put this solution on YOUR website!
(A)
10% of 20 pounds is:
.1%2A20+=+2
It contains 2 pounds of peanuts
(B)
10% of x pounds is:
.1x pounds of peanuts


Quadratic_Equations/220641: Sammy spends 10 Euros on some cans of drink. In another shop she sees that the same cans are each 10 cents cheaper, and she calculates that she could have brought 5 more cans for the same money. How many cans did she buy?
1 solutions

Answer 165604 by josmiceli(9661) About Me  on 2009-10-02 10:09:36 (Show Source):
You can put this solution on YOUR website!
Let x = number of cans bought
given:
10%2Fx = price per can in euros
In the other shop, price per can = 10%2Fx+-+.1
The same money is 10 euros, so
10+=+%2810%2Fx+-+.1%29%2A%28x+%2B+5%29
10+=+10+-+.1x+%2B+50%2Fx+-+.5
.5+=+50%2Fx+-+.1x
.5x+=+50+-+.1x%5E2
5x+=+500+-+x%5E2
x%5E2+%2B+5x+-+500+=+0
by quadratic equation:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a+=+1
b+=+5
c+=+-500
x+=+%28-5+%2B-+sqrt%28+5%5E2-4%2A1%2A%28-500%29+%29%29%2F%282%2A1%29+
x+=+%28-5+%2B-+sqrt%28+25+%2B+2000+%29%29%2F2+
x+=+%28-5+%2B-+45%29%2F2+
x+=+%28-5+%2B+45%29%2F2
x+=+20 (reject the negative solution)
She bought 20 cans
check answer:
10+=+%2810%2Fx+-+.1%29%2A%28x+%2B+5%29
10+=+%2810%2F20+-+.1%29%2A%2820+%2B+5%29
10+=+%28.5+-+.1%29%2A25
10+=+.4%2A25
10+=+10
OK


Linear-equations/220660: I have word problem.
A medium pizza costs $10.95, a large pizza costs $14.95. On a given day 50 pizzas were sold at a cost of $663.50. How many medium and how many large pizzas were sold.
How do I set this up
thanks.
1 solutions

Answer 165597 by josmiceli(9661) About Me  on 2009-10-02 09:36:12 (Show Source):
You can put this solution on YOUR website!
Let m = number of medium pizzas sold
Let l = number of large pizzas sold
given:
(1) m+%2B+l+=+50
66350 = cash received for 50 pizzas (in cents)
------------------
1095m = cash from medium pizzas (in cents)
1495l = cash from large pizzas (in cents)
(2) 1095m+%2B+1495l+=+66350
I have 2 equations with 2 unknowns, so it's solvable
Multiply both sides of (1) by 1095 and subtract
from (2)
(2) 1095m+%2B+1495l+=+66350
(1) -1095m+-+1095l+=+-54750
400l+=+11600
l+=+29
and, since
(1) m+%2B+l+=+50
m+%2B+29+=+50
m+=+21
21 medium and 29 large pizzas were sold
check answer:
(2) 1095m+%2B+1495l+=+66350
1095%2A21+%2B+1495%2A29+=+66350
22995+%2B+43355+=+66350
66350+=+66350
OK


Travel_Word_Problems/220538: Rick robbed a bank and left town at 64 mph. His crime was discovered 45 minutes later when the sheriff took off in hot pursuit at 80 mph. How long until the sheriff catches up?
1 solutions

Answer 165544 by josmiceli(9661) About Me  on 2009-10-01 22:39:33 (Show Source):
You can put this solution on YOUR website!
Assume I have a stopwatch. I will start the stopwatch
when the sheriff leaves. At that time, Rick has travelled
d%5Br%5D+=+64%2A%283%2F4%29 (45 min is 3/4 of an hour)
d%5Br%5D+=+48 mi
So, Rick has a 48 mi headstart
From this headstart to where the sheriff catches him,
call d in miles
For the sheriff:
d+%2B+48+=+80%2At
For Rick:
d+=+64%2At
By substitution:
64t+%2B+48+=+80t
16t+=+48
t+=+3hrs
The sheriff catches him 3 hrs after the sheriff leaves town
check answer:
d+=+64t (for Rick)
d+=+64%2A3
d+=+192 mi
So, Rick went a total of 48+%2B+192+=+240 mi at 64 mi/hr
The sheriff went 240 mi also at 80 mi/hr
For Rick:
240+=+64%2At%5Br%5D
t%5Br%5D+=+3.75 hrs for the whole trip for Rick
For Sheriff:
240+=+80%2At%5Bs%5D
t%5Bs%5D+=+3 hrs for the whole trip for Sheriff
Note that 3.75+-+3+=+.75, which is
the 45 min headstart that Rick had


Money_Word_Problems/220551: At the Glamour Boutique, a bottle of Allura Numero 75 perfume costs as much as two bottles of Exotic Mist. Mrs. Hampton bought one bottle of each and paid $24.00. How much does a bottle of Allura cost?
1 solutions

Answer 165535 by josmiceli(9661) About Me  on 2009-10-01 22:15:58 (Show Source):
You can put this solution on YOUR website!
Let a = cost per bottle of Allura
Let e = cost per bottle of Exotic Mist
given:
a+=+2e
a+%2B+e+=+24
By substitution:
2e+%2B+e+=+24
3e+=+24
e+=+8
and
a+=+2e
a+=+2%2A8
a+=+16
A bottle of Allura cost $16


Travel_Word_Problems/220543: I need help solving the problem:
The Great Seto Bridge in Japan is about 7.6 mi long. How long would it take you to cross the bridge if you were walking at 3mi/hr?
This is what I have done:
I set up a chart:
Rate:4 Time:t Distance:7.6

So would it be 4t=7.6?
I have no idea what I am doing. Please help. Your guidance would be greatly appreciated.
Thank you.
-Michelle
(Freshman)
1 solutions

Answer 165531 by josmiceli(9661) About Me  on 2009-10-01 22:09:42 (Show Source):
You can put this solution on YOUR website!
d+=+r%2At
given:
r+=+4+ mi/hr
d+=+7.6 mi
7.6+=+4%2At
Divide both sides by 4
t+=+7.6%2F4
t+=+1.9 hrs
It would take 1.9 hrs to cross bridge


Mixture_Word_Problems/220473: Help with word problem for Algebra 1
The nutty food company sells trail mixes by the pound. There are peanuts, raisin, ans carob-coated pretzels. The mgr. wants to make 80 pounds of this mixture and sell it for $3.35 per pound. Peanuts sell for $ $3.20 per pound, raisins sell for $ 2.40 per pound, and the carob pretzels sell for for $4.00 per pound. If the mixture has TWICE as many pounds of pretzels as raisons, how many pounds of each ingredient should the clerk use?
1 solutions

Answer 165527 by josmiceli(9661) About Me  on 2009-10-01 22:03:54 (Show Source):
You can put this solution on YOUR website!
Let p = pounds of peanuts needed
Let r = pounds of raisins needed
Let c = pounds of carob pretzels needed
given:
(1) p+%2B+r+%2B+c+=+80
(2) c+=+2r
(2) r+=+c%2F2
Cost of peanuts in mixture = 3.2p
Cost of raisins in mixture = 2.4r
Cost of Carob pretzels in mixture = 4c
--------------------------------------------
(3) 3.2p+%2B+2.4r+%2B+4c+=+3.35%2A80
(3) 320p+%2B+240r+%2B+400c+=+26800 (units are cents)
Multiply both sides of (1) by 240 and
subtract from (3)
(3) 320p+%2B+240r+%2B+400c+=+26800
(1) -240p+-+240r+-+240c+=+-19200
80p+%2B+160c+=+7600
Divide both sides by 80
p+%2B+2c+=+95
p+=+95+-+2c
Substitute this result and (2) in (1)
(1) p+%2B+r+%2B+c+=+80
95+-+2c+%2B+c%2F2+%2B+c+=+80
190+-+4c+%2B+c+%2B+2c+=+160
-c+=+-30
c+=+30
and
p+=+95+-+2c
p+=+95+-+2%2A30
p+=+95+-+60
p+=+35
and
r+=+c%2F2
r+=+30%2F2
r+=+15
The clerk should use 35 lbs of peanuts, 15 lbs of raisins,
and 30 lbs of carob-coated pretzels
check answer:
320p+%2B+240r+%2B+400c+=+26800
320%2A35+%2B+240%2A15+%2B+400%2A30+=+26800
11200+%2B+3600+%2B+12000+=+26800
26800+=+26800
OK




real-numbers/220463: Find a number between 11/12 and 1.
1 solutions

Answer 165500 by josmiceli(9661) About Me  on 2009-10-01 20:32:35 (Show Source):
You can put this solution on YOUR website!
If I add 1%2F12 to 11%2F12 I get 12%2F12+=+1,
so I need a fraction less than 1%2F12.
One-half of 1%2F12 is 1%2F24
11%2F12+%2B+1%2F24+=+22%2F24+%2B+1%2F24
22%2F24+%2B+1%2F24+=+23%2F24
23/24 is a number between 11/12 and 1
check:
11%2F12+=+.9167
23%2F24+=+.9583
OK


Money_Word_Problems/220203: A bookstore priced all hardback books at $5 a book and all paper back books at $1. The store sold 30 more paper backs than hardbacks. Total sales were $354. How many of each type were sold.
1 solutions

Answer 165394 by josmiceli(9661) About Me  on 2009-10-01 13:55:39 (Show Source):
You can put this solution on YOUR website!
Let h = number of hardbacks soold
Let p = number of paperbacks sold
given:
p+=+h+%2B+30
(1) p+-+h+=+30
and
(2) 1%2Ap+%2B+5h+=+354
Multiply both sides of (1) by 5 and add to (2)
5p+-+5h+=+150
p+%2B+5h+=+354
6p+=+504
p+=+84
and
p+=+h+%2B+30
84+=+h+%2B+30
h+=+54
84 paperbacks and 54 hardcovers were sold
check answer:
(2) 1%2Ap+%2B+5h+=+354
84+%2B+5%2A54+=+354
84+%2B+270+=+354
354+=+354
OK


Money_Word_Problems/220231: I know the answer is 2014. I just don't understand how this was calculated. Please help me.
Sonja and Chris both accept new jobs on March 1, 2001. Sonja starts at $44,000 with a raise each March 1 of 2%. Chris starts at $28,000 with a raise on March 1 each year of 6%. In what year will Chris' salary exceed Sonja's?
1 solutions

Answer 165391 by josmiceli(9661) About Me  on 2009-10-01 13:45:29 (Show Source):
You can put this solution on YOUR website!
The situation can be modelled as 2 linear equations
Let Salary, S, be plotted on the vertical axis
Let Years, Y, be plotted on the horizontal axis (staring at zero)
For Sonja,
(1)S+=+44000+%2B+.02%2A44000%2AY
For Chris,
(2)S+=+28000+%2B+.06%2A44000%2AY
I can rewrite them as
(1) S+=+44000%2A%281+%2B+.02Y%29
(2) S+=+28000%2A%281+%2B+.06Y%29
I'll find out in what year Salaries are equal
44000%2A%281+%2B+.02Y%29+=+28000%2A%281+%2B+.06Y%29
Divide both sides by 28000
%2811%2F7%29%2A%281+%2B+.02Y%29+=+1+%2B+.06Y
11%2F7+%2B+%2822%2F700%29%2AY+=+1+%2B+%286%2F100%29%2AY
%2842%2F700%29%2AY+-+%2822%2F700%29%2AY+=+11%2F7+-+7%2F7
%2820%2F700%29%2AY+=+4%2F7
Y+=+%2870%2F2%29%2A%284%2F7%29
Y+=+20
Their salaries will be equal in 20 years
Chris's will exceed Sonja's in 21 years,
or March 1st, 2022.
If you're sure the answer is 2014, then I made a
mistake, but I think the method is OK.
I'll plot them:




Triangles/220233: Find the altitude of an equilateral triangle that has side lengths of 4y. Express your answer in simplest radical form.
I am a homeschooling mom and don't remeber how to do this. Our book doesnt help either.
1 solutions

Answer 165378 by josmiceli(9661) About Me  on 2009-10-01 13:11:33 (Show Source):
You can put this solution on YOUR website!
The interior angles of an equilateral triangle
are 60-60-60, which adds up to
180 degrees, as they should.
The altitude divides the triangle into two
30-60-90 triangles, with the altitude being
opposite the 60 degree angle.
Call the altitude h
In this right triangle, sin%2860%29+=+h%2F%284y%29,
and sin%2860%29+=+sqrt%283%29%2F2
h%2F%284y%29+=+sqrt%283%29%2F2
Solve for h
h+=+4y%2Asqrt%283%29%2F2
h+=+2y%2Asqrt%283%29


Probability-and-statistics/220227: Two cards are drawn in succession from an ordinary deck of 52 bridge cards without replacement of the first card. Find the probability that both cards are a Queen.


1 solutions

Answer 165376 by josmiceli(9661) About Me  on 2009-10-01 12:58:18 (Show Source):
You can put this solution on YOUR website!
There are 4 queens, so on the 1st draw
the probability of getting one is
4%2F52
Now there are 51 cards in the deck,
and if you got a queen, there are 3 queens left
The probability of getting one is
3%2F51
When you want the probability of getting A and B
you multiply, so
%284%2F52%29%2A%283%2F51%29+=+1%2F221
The probability of drawing 2 queens in a row is 1/221


Mixture_Word_Problems/220223: I can't figure this one out and it's due yesterday! please help! i can do the conversion part, but factoring in the '18%' is stumping me...
thank you!
{{You work in a factory that makes chocolate chip cookies. Your cookies contain 18% by weight chocolate chips. If your boss tells you that yesterday, the factory used up 300 lbs. of chocolate chips, how many kilograms of cookies did the factory make?}}
1 solutions

Answer 165375 by josmiceli(9661) About Me  on 2009-10-01 12:49:54 (Show Source):
You can put this solution on YOUR website!
Let x = pounds of cookies the factory made
.18x+=+300
x+=+1666.66667 lbs
1 lb = .45359 kg
1666.66667 lbs x .45359 kg/lb = 755.983 kg
The factory made 755.983 kg of cookies


Travel_Word_Problems/219900: One lawn care woker can mow 3 lawns in 60 min. and another can mow 5 lawns in 75 min. How long will it take them to mow 7 lawns together?
1 solutions

Answer 165251 by josmiceli(9661) About Me  on 2009-09-30 20:18:08 (Show Source):
You can put this solution on YOUR website!
This is a rate problem
In general:
(1st worker's rate) + (2nd worker's rate) = (rate working together)
given:
1st worker's rate = 3%2F60+=+1%2F20 lawns/min
2nd worker's rate = 5%2F75+=+1%2F15 lawns/min
1%2F20+%2B+1%2F15+=+7%2Ft
Multiply both sides by 60t
3t+%2B+4t+=+420
7t+=+420
t+=+60 min
It takes them 1 hr to mow 7 lawns working together


Equations/219890: i am really struggeling e=wtih my homework.
i am in 7th grade and in pre-algebra
my question is that i need a algebra equation that EQUALS 29
and only using A,B,C,D EACH ONLY ONCE.
A=1
B=2
C=3
D=4 FOR EXAMPLE:
(bc)+dxa
2x3=6+4=10x1= 10
so the answer would be 10
1 solutions

Answer 165246 by josmiceli(9661) About Me  on 2009-09-30 20:09:55 (Show Source):
You can put this solution on YOUR website!
There are probably lots of ways to
do this.
One way is
%28A+%2BB%29%2AC+%2B+D+=+29 where
A+=+6
B+=+8
C+=+2
D+=+1
Substituting these values:
%286+%2B+8%29%2A2+%2B+1+=+29
This is the same as
14%2A2+%2B+1+=+29
28+%2B+1+=+29
29+=+29
OK


Probability-and-statistics/219887: HOW MANY PEOPLE DO YOU NEED TO GATHER TO BE SURE THAT AT LEAST TWO OF THEM HAVE A BIRTHDAYS IN THE SAME MONHT?
1 solutions

Answer 165242 by josmiceli(9661) About Me  on 2009-09-30 20:00:50 (Show Source):
You can put this solution on YOUR website!
The answer is 13
If there are only 12 people, there is a
possibility that each has a birthday in a
different month


Linear_Equations_And_Systems_Word_Problems/219874: You have quarters and nickels. You have a total of 15 coins. Altogether you have a total of $1.55. how many coins do you have?
1 solutions

Answer 165239 by josmiceli(9661) About Me  on 2009-09-30 19:58:01 (Show Source):
You can put this solution on YOUR website!
Let n = number of nickels
Let q = number of quarters
given:
(1) n+%2B+q+=+15
(2) 5n+%2B+25q+=+155 (in cents)
---------------------------------
From (1)
q+=+15+-+n
Subsitute in (2)
(2) 5n+%2B+25q+=+155
5n+%2B+25%2A%2815+-+n%29+=+155
5n+%2B+375+-+25n+=+155
-20n+=+-220
n+=+11
And
q+=+15+-+n
q+=+15+-+11
q+=+4
You have 11 nickels and 4 quarters



Mixture_Word_Problems/219575: Hi, I have a solution/miture question. I can solve the problem just fine once I get it in the right order... but this one I'm having a hard time putting all the info where it belongs.
Q) A pharmacist has 20L of a 10% drug solution. How many liters of 5% solution must be added to get a mixture that is 8%?
If you could just help me get this in the right format I would would be so thankful!! Thanks!!!
Casie R
1 solutions

Answer 165101 by josmiceli(9661) About Me  on 2009-09-30 14:11:31 (Show Source):
You can put this solution on YOUR website!
Let x = liters of 5% solution to be added
It doesn't say what the drug is mixed with, so I'll
just call it water.
In words:
(liters of drug in final solution)/(liters of drug + water in final solution) = 8%
given:
In 20 liters of 10% solution, there is
.1%2A20+=+2 liters of drug
In x liters of the 5% solution there is
.05x liters of drug
-------------------------
%282+%2B+.05x%29%2F%2820+%2B+x%29+=+.08
2+%2B+.05x+=+.08%2A%2820+%2B+x%29
2+%2B+.05x+=+1.6+%2B+.08x
.03x+=+.4
x+=+13.333
The Pharmacist must add 13.333 liters of the 5% solution
check answer
%282+%2B+.05x%29%2F%2820+%2B+x%29+=+.08
%282+%2B+.05%2A13.333%29%2F%2820+%2B+13.333%29+=+.08
2.666%2F33.333+=+.07998
(error due to rounding -OK)



Expressions-with-variables/219570: A rubber ball is dropped from the height of 13.5 feet. After each bounce the ball only goes up by 60% of what it did on the previous bounce. How high will the ball go after the 38th bounce? I took the 13.5x .6 for the 1st bounce which is 8.1Ft. and the 2nd bounce is 4.9ft. and the third is 2.9ft. I could do this for all the bounces but it would take me forever. How can I write a formula to just put in bounce to get height?
1 solutions

Answer 165092 by josmiceli(9661) About Me  on 2009-09-30 13:54:37 (Show Source):
You can put this solution on YOUR website!
I'll try to write a general formula.
After the 1st and succeeding bounces,
h+=+.6%2A13.5
h+=+.6%2A.6%2A13.5
h+=+.6%2A.6%2A.6%2A13.5
It looks like the formula would be
h+=+13.5%2A.6%5En where n is the number of bounces
and h is the height after that bounce
After 38 bounces,
h+=+13.5%2A.6%5E38
h+=+13.5%2A3.713%2A10%5E%28-9%29
h+=+5.0128%2A10%5E%28-8%29 ft
How much is that in millionths of an inch?
10%5E6%2A12+=+1.2%2A10%5E5 millionths of inch/ft
h+=+5.0128%2A10%28-8%29%2A1.2%2A10%5E5
h+=+6.015%2A10%5E%28-3%29
That looks like h+=+6.015 billionths
of an inch after the 38th bounce


Probability-and-statistics/219499: A car radiator contains 10 liters of 20% anitfreeze solution. How many liters of pure antifreeze are needed to make the solution 50% antifreeze without replacement?
1 solutions

Answer 165054 by josmiceli(9661) About Me  on 2009-09-30 11:54:12 (Show Source):
You can put this solution on YOUR website!
This assumes that the radiator will hold whatever added
antifreeze you try to put in.
In words:
(final liters of antifreeze)/(final liters of total mixture) = 50%
Let a = liters of antifreeze to be added
%28.2%2A10+%2B+a%29%2F%2810+%2B+a%29+=+.5
Multiply both sides by 10+%2Ba
2+%2B+a+=+.5%2A%2810+%2B+a%29
2+%2B+a+=+5+%2B+.5a
.5a+=+5+-+2
.5a+=+3
a+=+6
6 liters of antifreeze needs to be added to make mixture 50%
check answer:
%28.2%2A10+%2B+6%29%2F%2810+%2B+6%29+=+.5
%282+%2B+6%29%2F16+=+.5
8%2F16+=+.5
.5+=+.5
OK


Money_Word_Problems/219496: How long does it take your money in your savings account to double at 8% interest rate using the formula A=Pe^rt ?
1 solutions

Answer 165052 by josmiceli(9661) About Me  on 2009-09-30 11:45:09 (Show Source):
You can put this solution on YOUR website!
A+=+Pe%5E%28rt%29
P is the original amount invested. The problem
wants to know how long (what t is) it takes to
make A twice this amount, so A+=+2P
2P+=+Pe%5E%28rt%29
given:
r+=+.08 (this is annual intest rate)
2P+=+Pe%5E%28.08t%29
Divide both sides by P
2+=+e%5E%28.08t%29
Take the natural log of both sides
ln%282%29+=+.08t
.69315+=+.08t
t+=+8.664 (t is the time in years)
I can find .664 years in months also
.664%2A12+=+7.9 (about 8 months)
It takes 8 years and 8 months to double money



Travel_Word_Problems/219153: how long will it take to drive 50 feet at 25mph?
1 solutions

Answer 164898 by josmiceli(9661) About Me  on 2009-09-29 19:44:55 (Show Source):
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5280ft = 1 mile
25 mi/hr x 5280 ft/mi = 132000 ft/hr
Set up equation:
d+=+r%2At
50+=+132000%2At
t+=+.000378788 hrs
Note that
60 min/hr x 60 sec/min = 3600 sec/hr
.000378788 hrs x 3600 sec/hr = 1.3636 sec
It will take 1.3636 sec to drive 50 ft


Numbers_Word_Problems/219202: the sum of two consecutive numbers divided by three equals seventy one?
1 solutions

Answer 164893 by josmiceli(9661) About Me  on 2009-09-29 19:35:56 (Show Source):
You can put this solution on YOUR website!
The consecutive numbers are
n
n%2B1
given:
%28n+%2B+n%2B1%29%2F3+=+71
%282n+%2B+1%29%2F3+=+71
2n+%2B+1+=+213
2n+=+212
n+=+106
n+%2B+1+=+107
The numbers are 106 and 107
check:
%28n+%2B+n%2B1%29%2F3+=+71
%28106+%2B+107%29%2F3+=+71
213%2F3+=+71
213+=+213
OK