Work done by A in one day is half of the work done by B in one day. Work done by B is half of the work done by C in one day. If C alone can do the work in 7 days, then in how many days can A, B and C together complete the work?

4

Work done by A in one day = 0.5 * (Work done by B in one day)

Also, Work done by B in one day = 0.5 * (Work done by C in one day)

C can complete the work in 7 days.

C's one day Work = 1/7

Work done by B in one day = 1/14

Work done by A in one day = 1/28

One day work done if A, B, C work together = 1/7 + 1/14 + 1/28 = (4+2+1)/28 = 1/4

Time taken by A,B and C working together = 4 days

The correct answer is Option (1) → 4