Question

A can do a work in 40 days. He worked at it for 8 days and then b finished it in 16days. How long will they together take to complete the work?

Answer 1

Hi there!
Here's the answer:

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A can do a work in 40 days
He worked for 8 days

=> Work done by A in 8 days = $(\frac{1}{40} × 8) = \frac{1}{5}$

Work Remained =$(1 - \frac{1}{5}) = \frac{4}{5}$

This $\frac{4}{5}$ work is done by B in 16 days

=> No. of days taken by B to do the work
= $(16 × \frac{5}{4}) = 20 days$

•°• A's 1 day work = $\frac{1}{40}$
& B's 1 day work = $\frac{1}{20}$

(A+B)'s 1 day work = $(\frac{1}{40} + \frac{1}{20}) = \frac{3}{40}$

•°• If A and B worked together they will take $\frac{40}{3} days = 13\frac{1}{3} days$

= $13 days\: and\: (\frac{24}{3}) hrs$

= $13 days\: and\: 8 hrs$

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:)

Hope it helps