Question 72

A and B can do a piece of work alone in 15 and 30 days respectively. In how many days can they together complete the work?

Solution

A and B can do a piece of work alone in 15 and 30 days respectively.

LCM of 15 and 30 is 30 which can be assumed as the total work.

The efficiency of A = $$\frac{30}{15}$$ = 2 units/day

The efficiency of B = $$\frac{30}{30}$$ = 1 unit/day

Time is taken by A and B together to complete the work = $$\frac{30}{\left(1+2\right)}$$

= $$\frac{30}{3}$$

= 10 days

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