Question

A group of 9 workers was assigned to paint the walls in a house, which could be completed in 48 hours. However, after working 8 hours, some of the workers left the group and the remaining workers could complete the job in 72 hours. How many workers left the team?

Answer 1

4 workers

Explanation:

A group of 9 workers was assigned to paint the walls in a house, which could be completed in 48 hours. Then 1 worker will complete the whole job in
`48* 9=432` hours.

If 1 worker completes the whole work in 432 hours, then he completes
`(1)/(432)` of the work per hour.

9 workers complete
`9*(1)/(432)=(1)/(48)` of work per hour and complete
`(1)/(48)* 8=(1)/(6)` of work in 8 hours.

`1-(1)/(6)=(5)/(6)` of work left.

This could be completed by n workers in 72 hours, so

`(n)/(432) * 72=(5)/(6)\\ \\(n)/(6)=(5)/(6)\\ \\n=5`

9 - 5 = 4 workers left the team.