SOLUTION: It takes 2 people together 12 minutes to wash a car. One person by himself takes 21 minutes. How long would it take the other person to wash the car?
I know it cannot be that on
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-> SOLUTION: It takes 2 people together 12 minutes to wash a car. One person by himself takes 21 minutes. How long would it take the other person to wash the car?
I know it cannot be that on
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Question 625945: It takes 2 people together 12 minutes to wash a car. One person by himself takes 21 minutes. How long would it take the other person to wash the car?
I know it cannot be that one can wash the car in 6 minutes but I am stuck with this question.
Thank you Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! It takes 2 people together 12 minutes to wash a car.
One person by himself takes 21 minutes.
How long would it take the other person to wash the car?
:
Time varies inversely with no. of people, (more people, less time)
Therefore a typical shared work equation can be used.
:
Let a = time required by the other person alone
let the completed job = 1
Each person will do a fraction of the job, the two fractions add up to one.
: + = 1
multiply thru by 21a to clear the denominators, results
12a + 21(12) = 21a
252 = 21a - 12a
252 = 9a
a = 252/9
a = 28 minutes for the 2nd person to do it
:
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You can check this on a calc, enter 12/21 + 12/28
