Ten boys agree to paint the gym in five days. If five more boys join in before the work begins, how many days should the painting take?

Question

The possible answers are...

a. 3 1/3

b. 3 1/2

c. 2 1/2

d. 2 3/4

Answer 1

The answer is 3.333 (a)

Assume that they have to paint 1000 ft² (This is arbitrary, I could use any number!)

So, 1000 ft²/5 days means they paint 200 ft² per day. But they have 10 boys which means each boy paints

200/10 = 20 ft² per day per boy.

With 15 boys, they paint 15 x 20 ft²/day = 300 ft² per day but they have 1000 ft² to paint which means

Time will be 1000/300 = 3.333 days