P, Q and R can complete a piece of work in 10 days, 15 days and 20 days, respectively. If they work together, in how many days can they finish the same work?

Question

Question

This question was previously asked in

SSC CGL 2023 Tier-I Official Paper (Held On: 24 Jul 2023 Shift 1)

Answer 1

Given:

A can do the work in 10 days

B can do the work in 15 days

C can do the work in 20 days

Formula used:

Work done = Time taken × Efficiency

Time taken ∝ 1/Efficiency

Calculation:

1st day work by A = 1/10

2nd day work by B = 1/15

3rd day work by C = 1/30

Total work completed in 3 days

⇒ 1/10 + 1/15 + 1/20

⇒ (6 + 4 + 3)/60 = 13/60

Time taken to complete the work

⇒ 60/13

⇒ 4(8/13)

They finish the same work in 4(8/13) days.

Work done together in 1 day is:

⇒ 6 + 4 + 3 = 13

Total time required to complete the work ⇒ 60/13

⇒ \(4\frac{8}{13}\) days