Question

8 men will take 10 days to build a wall 150 metres long. After the men had started working for 6 days, they were told that the wall needed to by lengthened by 45 metres. How many more men must be hired to complete the job on time?​

Answer 1

First, find out how much each man works. If eight men take 10 days to build 150 m of wall, then that means that it takes 80 man days to build 150 m. One Man day is then 150÷80, in other words 1.875. If eight men have already been working for six days, then they have spent 8×6 man days, 48. 48 men days times 1.875 m of wall per man day equals 90 m of wall have been built. So, you have four days left to build the remaining 60 m of wall as well as 45 extra meters, in other words, 105 m total. 105 m divided by four days equals 26.25 m need to be built every day. Since one man builds 1.875 m of wall every day, to find the number of men total you need for the last four days, take 26.25÷1.875, Which equals 14 exactly. 14 is not the answer however, because it’s asking how many more men you need. Since you already have eight, you need six more to make 14

The answer is six more men