Question

at a construction site a group of 17 men could complete a task in 56days some men left due to I'll health and the work extended to 63 days more how many men took I'll and left the construction site ​

Answer 1

Answer:

In 12 days it takes 5 men to finish the work.

The tricky part is the following step. Most students make a mistake here because their concept is not clear and they follow a process blindly without knowing the reasons.

As a standard practice, they would say-

“ In 1 day it takes 5/12 men to finish the work.

Thus in 6 days, it would take 5/12 * 6 = 5/2 men to finish the work.”

We see that it is actually quite impossible because 5/2 men don’t exist, but had the problem dealt with numbers which would have led to whole numbers, not fractions, they would have proceeded with the mistake.

In place of standard formula if you use some common sense then you can observe something very easily:

In 12 days it takes 5 men to finish the work.

So in 1 day, it must take 5*12 = 60 men to finish the work. Obviously to do some work in 1 day you need more manpower.

Thus to finish the work in 6 days you would require 60/6 = 10 men