Question 86

A is thrice as efficient as B and takes 10 days less to do a piece of work than B takes to do the same work. In how many days, B alone can finish the whole work ?

Solution

Let total work be 1 unit

Let efficiency of A = $$3x$$ units/day

=> efficiency of B = $$x$$ units/day

Acc to ques :

=> $$\frac{1}{x} - \frac{1}{3x} = 10$$

=> $$\frac{2}{3x} = 10$$

=> $$x = \frac{1}{15}$$

$$\therefore$$ Time taken by B = 15 days

(Shortcut)

Since, A takes 10 days less than B, => B definitely takes more than 10 days

=> Options (B), (C) & (D) are eliminated.

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