|
Question 898136: a woman asked 10 boys to clean a 5 roomed house, they finished it in 30 minutes. How long will it take 15 boys to finish cleaning the house????
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! rate per person times number of people times time = quantity
r*p*t = q
quantity is 1 clean house.
t = 30 minutes
p = 10
you are solving for rate per person.
formula becomes:
r*10*30 = 1
divide both sides of the equation by 10*30 to get:
r = 1 / (10 * 30) = 1/300.
1 person can clean 1/300 of the house in 1 minute.
1/300 * 10 * 30 = 300 / 300 = 1 cleaned house, so the value of r is confirmed to be good.
r is the amount of the house tht 1 person can clean in one minute.
you have established that one person can clean 1/300 of the house in 1 minute.
now you want to know how long it would take 15 persons to clean the house.
the formula of r*p*t = q is used again, and becomes:
(1/300) * 15 * t = 1
now you want to solve for t.
you get t = (1 / 15) * 300 = 20 minutes.
10 boys can clean the house in 30 minutes.
15 boys can clean the house in 20 minutes, working at the same rate for each boy.
1/300 * 10 * 30 = 1
1/300 * 15 * 20 = 1
solution is it will take 15 boys 20 minutes to clean the house.
|
|
|
| |
