SSC CHSL 2024 PYQ — Question 53

The correct answer is option 4 i.e. 5 days.

Given that

A, B, and C can complete the work in = 12, 15, and 20 days respectively

Let the total work to be completed be = W units

Let us assume W units = L.C.M(12, 15, 20) = 60 units

Unit of work completed by A in 1 day = $\frac{60}{12}$ = 5 units

Unit of work completed by B in 1 day = $\frac{60}{15}$ = 4 units

Unit of work completed by C in 1 day = $\frac{60}{20}$ = 3 units

Units of work completed in a day by all three working together = 5 + 4 + 3 = 12 units

Hence, the time taken by all three working together to complete the work = $\frac{60}{12}$ = 5 days