Question

The time required to do a job varies inversely as the number of people working. It takes 6 hr for 8 bricklayers to build a park wall. How long will it take 7 bricklayers to complete the​ job?

Answer 1

It should be 5.25 hours

Since it took 6 hours to build 8 bricklayers then it should take less time to build a 7 bricklayers

First, set a proportion:
Hours/bricklayers
6/8 = x/7

Then cross-multiply: 8x=42

And finally, solve:

x=5.25 hours

Answer 2

6 6/7 hrs

Explanation:

The general equation for inverse proportion is y = k/x, where k is the constant of proportionality. We need to determine the value of k from the given data:

y = k/x becomes 6 = k/8, so that k = 48.

Then y = 48/x represents the length of time required for x bricklayers to build the wall.

If there are 7 bricklayers, then x = 7, and y = 48/7

It requires 7 bricklayers 48/7 hours (6 6/7 hours) to build the wall.