Ques:- Thirty men take 20 days to complete a job working 9 hours a day. How many hour a day should 40 men work to complete the job?
A. 8 hrs
B. 7 1/2 hrs
C. 7 hrs
D. 9 hrs
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7 1/2 hrs
(30Men x 20days x 9hrs)/(40Men) = 135 hrs per day. Which
is impossible. So, the answer is none.
Since the question is vague, if you don’t answer this
question you may be given mark for this question.
The question should have been
1. How many days 40 men working 9 hrs a day will take to
complete the work.
Answer: (30Men x 20days x 9hrs)/(40Men x 9 hrs) = 15days
2. How many hours a day should 40 men work for 20days will
take to complete the work.
Answer: (30hrs x 20day x 9hrs)/(40Men x 20days)=6 3/4 hrs
Answer should be 9hrs, if in the question, no. Of working days remain same
ans : (b)
30 mem in 180hrs in 20 days
efficiency of each person is 1/180*30
efficiency of 40 mem is 40/180*30 = 1/45*3
no.of hrs per day = 45*3/20 = 7.22 hrs (app)
7 1/2