If it takes 10 children 15 minutes to paint a wall, how long would 15 students take to paint the same wall?

Question

I am so confused. Do you have to first find how long one child would take then multiply??

Answer 1

it takes a total of

10 x 15 = 150 person-minutes to paint the wall

meaning that if you now have 15 people that would take

150 / 15 = 10 minutes

Answer 2

That would vary inversly, because more children should get the wall painted faster.

 

10 children/15 minutes = m minutes/15 children

 

Normally you would cross multiply and solve for m, but I bet you can look at it and give an answer for m.