A contract is to be completed in 52 days and 125 identical robots were employed, each operational for 7 hours a day. After 39 days, five-sevenths of the work was completed. How many additional robots would be required to complete the work on time, if each robot is now operational for 8 hours a day?
A. 50 B. 89 C. 148 D. 175
GATE 2018 · General Aptitude · Work Time · medium
Answer: 50 additional robots are needed (Option A). (Answer key excludes this question but the computed correct value is 50.)
Total robot-hours in phase 1: Phase 1 = 125 × 7 × 39 = 34,125 robot-hours for 5/7 of work.