Question

A, B, and C can do a piece of work in 12, 15, and 20 hours respectively. How long ill they take to do the work together?

Answer 1

Answer:

If they work together:

Let t be the time they take to work.

1/t = 1/12 + 1/15 + 1/20

1/t = 1/5

t = 5 hours

Answer 2

Answer:

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Step-by-step explanation:

Let the Time taken to complete the work together be=t

Therefore,

$\frac{1}{t} = \frac{1}{12} + \frac{1}{15} + \frac{1}{20} \\ \Rightarrow \frac{1}{t} = \frac{1}{5}$

so,they will take 5hr. to complete the work