Question

Solve the following.

5 men can build a wall 20ft long in 7 days. Find the length of the wall built by 13 men in 21 days?

Answer 1

Let x be the length of wall made by 13 men in 21 days.

Length of wall increases, when the required number of men increase.

This is direct proportion.

The detailed proportions are:

Men	Days	Length
5	7	20
13	21	x

Thus, length of the wall made by 13 men in 21 days is 156 ft.