Multiple choice

A can do a piece of work in 5 days, B can do it in 10 days and C can do it in 30 days. They together can do the whole work in -

  1. 5 days

  2. 3 days

  3. 10 days

  4. 15 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A's 1 day work = 1/5, B's 1 day work = 1/10, C's 1 day work = 1/30. Together in 1 day = 1/5 + 1/10 + 1/30 = (6+3+1)/30 = 10/30 = 1/3. So they complete the work together in 3 days. Add individual efficiencies, then invert to get total time.

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