Question

P can complete a piece of work in 8 days, Q in 10 days and R in 12 days. Q and R together worked for 3 days, then R left the work and P replaced him. In how many days will the remaining work be completed?

a) 2 days b) 4 days c) 3 days d) 1 day e) 5 days

Answer 1

P,Q,R LCM are 120(unit work of 1 day)

Q and R 1day work in unit = 120÷10 + 120÷12= 12 + 10 = 22(1day work in unit)

3 days work = 3×22 = 66

remaining work in unit = 120 - 66 = 54

P and Q are 1day work = 120÷8 + 120÷10 = 15 + 12 = 27 (1day unit work)

so 54÷ 27 = 2(days)