A contractor agreeing to finish a work in 150 days, employed 75 men each working 8 hours daily. After 90 days, only \(2 / 7\) of the work was completed. Increasing the number of men by and each one is working now for 10 hours daily, the work can be completed in time.
A. 75 B. 225 C. 150 D. 100 E. 175
Correct Answer: C
Explanation
Total hours worked by 75 men \(=90 \times 8=720\) Man-hours put in \(=720 \times 75=54000\) man-hours In so many man-hours, \(2 / 7\) of the work is completedraction of work left \(=1-2 / 7=5 / 7\) This will take \(=54000 \times(5 / 7) /(2 / 7)=135000\) man-hours \(\because\) No. of hours to be worked for remaining days \(=60 \times 10=600\) \(\therefore\) No. of men to be employed \(=135000 \div 600=225\) \(\therefore\) Additional men to be employed \(=225-75=150\)
