Question

C.
31 days
129. A can do a piece of work in 5 hours, B in 9 hours. and c in 15 hours If C
for one hour only, how long would A and B take to do the worked with them
work together ?
4 hrs
b. 31 hours
a.​

Answer 1

Step-by-step explanation:

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Answer 2

Explanation:

Time taken by A to do the work = 5 hours

Work done by A in 1 hour

$= \frac{1}{5}$

Time taken by B to do the work = 9 hours

Work done by B in 1 hour

$= \frac{1}{9}$

Time taken by C to do the work = 15 hours

Work done by C in 1 hour

$= \frac{1}{15}$

Therefore, remaining work

$= 1 - \frac{1}{15} = \frac{14}{15}$

Work done by A and B together in 1 hour

$= \frac{1}{5} + \frac{1}{9} = \frac{9 + 5}{45}$

$= \frac{14}{45}$

Therefore, time taken by A and B to do the remaining work

$= \frac{14}{15} \div \frac{14}{45} = \frac{14}{15} \times \frac{45}{14}$

$= 3 \: days$

Answer: 3 days

I hope this helps. :)