Question

a contractor who had a work froce of 630persons undertook to complete a portion of a stadium in 14 months he was asked to complete the job in 9 months how many extra persons had he to employ

Answer 1

Number of workers = 630
Time taken to complete the work = 14months

Time in which job has to be completed = 9months

Let's solve it with the help of variation.
See, here time is reduced, but if time is reduced then workers will I increase.

Therefore, this is a case of inverse variation.
In inverse variation xy=k

Now, 630×14 = 9×Number of workers needed.
Number of workers needed = 630×14/9 = 70×14 = 980

Extra employees needed = Workers needed now - Workers present earlier
= 980 - 630
= 350

Hence, 350 employees are needed. Hope that helps