Question

A can do 1/6 piece of work in 2 hours and B can 1/4 of the same work in 5 hours. in how many hours can both do it together?

Answer 1

Answer:

For A ----

1/6 of work in 2 hours.

Therefore, complete work in 2*6 hours =12hrs.

For B----

1/4 of work in 5 hours.

Therefore, complete work in 4*5 hrs=20hrs.

They can together do the work in 1 / (1/12+1/20) =20*12/12+20 =240/32 =7.5 hours.

Answer 2

Answer:

In 8.5 hours (Approx.) both A and B can complete the work.

Step-by-step explanation:

According to the question,

A can do 1/6 piece of work in 2 hours, i.e.,

The time taken by A to do 1/6 piece of work = 2 hours

So, the time taken by A to do whole work = $\frac{2}{1/6}$

                                                                       = 12 hours

Similarly,

B can do 1/4 piece of the same work in 5 hours, i.e.,

The time taken by B to do 1/4 piece of the same work = 5 hours

So, the time taken by B to do whole work = $\frac{5}{1/4}$

                                                                       = 20 hours

Hence, the time taken by A and B to complete the work together is,

= $\frac{1}{12}+\frac{1}{20}$

= $\frac{5+3}{60}$

= 7/60

Therefore, in 60/7(8.5 approx.) hours, both A and B can complete the work.

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