A can lay a railway track between two given stations in 8 days and B can do the same job in 24 days. With the help of C, they can do the job in 3 days. C alone can do the job in:

Question

Question

This question was previously asked in

RRB NTPC Graduate Level CBT-I Official Paper (Held On: 09 Jun, 2025 Shift 1)

Answer 1

Given:

A can do the work in = 8 days

B can do the work in = 24 days

A + B + C can do the work in = 3 days

Formula used:

Work done per day = 1 / Number of days

Total work = LCM of all given days

Calculation:

let the total work = LCM of 8, 24, 3 = 24 units

A’s 1-day work = 24 ÷ 8 = 3 units

B’s 1-day work = 24 ÷ 24 = 1 unit

(A + B + C)’s 1-day work = 24 ÷ 3 = 8 units

⇒ C’s 1-day work = 8 − (3 + 1) = 8 − 4 = 4 units

⇒ Time taken by C alone = 24 ÷ 4 = 6 days

∴ C alone can do the job in 6 days.

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