mitaliisrani wrote:P, Q R individually can complete a piece of work in 8, 12, 24 days. P and R start working together, After 4 days, R quits is replaced by Q. In how many days is work completed
A) 1 3/5 days
B) 5 3/5 days
C) 4 2/5 days
D) 5 1/5 days
E) None of these
OA
B
When the job is undefined, we can plug in our own number for the job. To make the math easy, we should choose a number that is a multiple of 8, 12 and 24.
Job = 24.
Rate of P = work/time = 24/8 = 3/day.
Rate of Q = work/time = 24/12 = 2/day.
Rate of R = work/time = 24/24 = 1/day.
Combined rate of P and R = 3+1 = 4/day.
Work completed by P and R in 4 days = rate * time = 4*4 = 16.
Remaining work = 24-16 = 8.
Combined rate of P and Q = 3+2 = 5/day.
Time to complete the remaining work = work/rate = 8/5.
Total time for job = 4 + 8/5 = 5 3/5 days.
The correct answer is B.
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