Q:
A group of men can complete a job in K hours. After every 4 hours, half the number of men working at that point of time leave the job. Continuing this way if the job is finished in 16 hours, what is the value of K ?
Answer & Explanation
Answer: B) 7.5 hrs
Explanation: Let there are L men
job requires LK man hours.
job completed in first 4 hrs = L x 4 = 4L
job completed in next 4 hrs = 4 x L/2 = 2L
job completed in next 4 hrs = 4 x L/4 = L
job completed in last 4 hrs = 4 x L/8 = L/2
4L + 2L + L + L/2 = KL
K = 7+1/2 = 7.5 hours.
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