RRB Junior Engineer / DMS / CMA 2019 · Question 29 of 3719

P and Q can do a work in 10 days. Q and R can do it in 12 days. All three together can finish in 8 days. In how many days can P and R can complete the work?

Mathematics - Time and Work

Aa. 10 days
Bb. 8 days
Cc. 12 days
Dd. 15 daysCorrect

Answer: D. d. 15 days

Explanation

Let, total work = LCM of (10, 12 and 8) = 120 Efficiency of (P + Q) = 12 Efficiency of (Q + R) = 10 Efficiency of (P + Q + R) = 15 Efficiency of R = 15-12 = 3 Efficiency of P = 15-10 = 5 Efficiency of (P+R) = 3 + 5 = 8 P and R both complete the whole work in = 120/8 = 15 days

Source: RRB JE 2019 CBT-1 (24-May-2019 Shift-2) — ixambee compilation with answer key and solutions · reliable-secondary

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