P and Q together can complete a work in 105 days. Q and R together can complete the same work in 90 days, P and R together can complete the same work in 126 days. In how many days P, Q and R together can complete the same work?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 70 days
| Understanding | Application |
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Let total work be LCM of 105, 90,and 126 = 630 Efficiency of P + Q = 630/105 = 6 Efficiency of Q + R = 630/90 = 7 Efficiency of R + P = 630/126 = 5 Efficiency of P + Q + R = (6 + 7 + 5)/2 = 9 Time taken by P,Q,R to complete the work together = 630/9 = 70 Days
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Efficiency = Total work/Time |