Question

A Contractor employed a certain number of workers to finish constructing a road in a certain scheduled time. Sometime later, when a part of work had been completed, he realised that the work would get delayed by three-fourth of the scheduled time, so he at once doubled the no of workers and thus he managed to finish the road on the scheduled time. How much work he had been completed, before increasing the number of workers?

A) 10 % B) 14 ( 2/7 )% C) 20 % D) Can't be determined

Answer 1

Answer is C) 20% I hope it is correct

Answer 2

Answer:

The correct answer is option B

Step-by-step explanation:

Method1:

Let initially x people were employed to do the work in y days and after z days there number was doubled. If they continue to do the work on their initial pace, the work would have done in $\frac{7}{4} y \ days$  

So we have

 $\frac{7}{4} xy=xz+2x(y-z)\\\frac{7}{4} xy=xz+2xy-2xz\\\\frac{7}{4} xy=2xy-xz\\z=\frac{1}{4}y$

Now let initially 10 people were employed to do the work in 4 days.

Since $z=\frac{1}{4}y$  so the number was doubled after one day.

In the first day, 10 people did 10 man days work and then their number was doubled, so the 20 men did 60 man days work in the remaining 3 days.

Hence the total work was 70 man days out of which 10 man days work was done before employing new people.

Hence the required % age of work done before increasing the number of workers $\frac{10}{70} *100=\frac{100}{7} \\=14\frac{2}{7}$

Method 2:

Let he initially employed x workers which works for D days and he estimated 100 days for the whole work and then he doubled the worker for (100-D) days.

D * x +(100- D) * 2x= 175x

=>  D= 25 days

Now , the work done in 25 days = 25x

Total work = 175x

Therefore, work done before increasing the no of workers =$\frac{25x}{75x} *100\\x=14\frac{2}{7}$

Reference  Link

• https://brainly.in/question/2177479
• https://brainly.in/question/15803999