Multiple choice

A contractor undertakes to dig a canal, $6$ kilometers long in $35$ days and employed $90$ men. He finds that after $20$ days only $2$ km of canal have been completed . How many more men must be employed to finish the work in time?

  1. $120$ men
  2. $170$ men
  3. $180$ men
  4. $150$ men
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The work formula is (M1*D1)/W1 = (M2*D2)/W2. Initially, 90 men did 2 km in 20 days. Remaining work is 4 km in 15 days. (90*20)/2 = (M2*15)/4. Solving gives M2 = 240. Since 90 men are already there, 150 more are needed.