Exams › SSC CGL (Prelims) › General

A can complete a task in 15 days, and B can complete the same task in 20 days. How long will it take them to complete the task together?

1. 5.5 days
2. 6.5 days
3. 7.5 days
4. 8.5 days

Correct answer: 8.5 days

Solution

A’s rate is \(1/15\) work/day and B’s rate is \(1/20\) work/day. Together, their rate is \(1/15+1/20=7/60\) work/day, so time taken is \(60/7\approx 8.57\) days.

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