Question 52

A, B and C can do a work in 12, 15 and 20 days respectively. In how many days, working together they can complete the same work?

Solution

LCM of 12, 15, and 20 is 60 which can be assumed as the total work.

A, B and C can do a work in 12, 15 and 20 days respectively.

The efficiency of A = $$\frac{60}{12}$$ = 5 units/day

The efficiency of B = $$\frac{60}{15}$$ = 4 units/day

The efficiency of C = $$\frac{60}{20}$$ = 3 units/day

Time taken by all of them together to complete the same work = $$\frac{60}{5+4+3}$$

= $$\frac{60}{12}$$

= 5 days

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