Two teachers A and B can complete an academic work in 10 days and 15 days respectively. They started the work together, but A left after 5 days and another teacher C joined, who alone can complete the work in 60 days. In how many days the work got completed?
Show answer & explanation
Correct answer: A
Explanation
Correct Answer is option 1 i.e. 7
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Understanding |
Application |
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A and B can complete an academic work in 10 days and 15 days respectively. C alone can complete the work in 60 days. |
Total unit of work = 60 (LCM of 10, 15 and 60) Efficiency of A = 60/10 = 6 Efficiency of B = 60/15 = 4 Efficiency of C = 60/60 = 1 First A and B started the work and A left after 5 days: Remaining work = 60 – (6 + 4) × 5 = 60 – 50 = 10 units After 5 days, C joined; Time in which remaining work is done = 10/(4 + 1) = 2 days Total time = 5 + 2 = 7 days |