Practice Test Discussion

A can do a piece of work in 8 hours while B alone can do it in 16 hrs. In how many hours, Both A and B working together can finish the work ?

$5 \frac{2}{3}$ hours

$5 \frac{3}{5}$ hours

$5 \frac{1}{5}$ hours

$5 \frac{1}{3}$ hours

None of these

Explanation

According to the question,

In 1 hour,

A can complete $\frac{1}{8}$ ^th of the work

B can complete $\frac{1}{16}$ ^th of the work

(A+B) together can complete $\frac{1}{8} + \frac{1}{16} = \frac{2 + 1}{16} = \frac{3}{16}$ ^th of the work

∴ (A+B) will complete the work in $\frac{16}{3} or 5 \frac{1}{3} h o u r s$

Hence option D is the correct.

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