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 ?
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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