A, B and C can do a piece of work in 20, 30 and 60 days, respectively. In how many days can A do the work if he is assisted by both B and C on every third day?

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Question

This question was previously asked in

SSC CGL 2023 Tier-I Official Paper (Held On: 27 Jul 2023 Shift 2)

Answer 1

Given:

A can do a work alone = 20 days

B can do a work alone = 30 days

C can do a work alone = 60 days

Formula used:

\(Work = Efficiency × Time\)

Calculation:

The efficiency of the A = \( {1\over 20}\)

The efficiency of the B = \( {1\over 30}\)

The efficiency of the C = \( {1\over 60}\)

The two-day work of A = \({2\over20}={1\over10}\)

The work done by A, B, and C together on third day = \({1\over20}+{1\over30}+{1\over 60}={3+2+1\over60}={6\over60}={1\over 10}\)

The first three days' work = \({1\over 10}+{1\over10}={2\over10}={1\over5}\)

The 20% work done by them in 3 days.

The whole work they can complete in = 3 × 5 = 15 days

∴ The required result will be 15 day.

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