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A is 50% more efficient than B and so finishes the work 15 hours before B finishes the same work. Find the time taken by A (in hours) to finish double the work.


1. 30 hours
2. 40 hours
3. 50 hours
4. 60 hours
5. 80 hours

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Best answer
Correct Answer - Option 4 : 60 hours

Given:

A is 50% more efficient than B.

Time is taken by A to finish the work = time taken by B – 15

Concept used:

Work = time × efficiency

When work done by A and B is the same, t ∝ 1/e; where ‘t’ is time and ‘e’ is efficiency.

Calculation:

The ratio of efficiency of A to B = 3 ∶ 2

The ratio of time of A to B = 2 ∶ 3

Then, time is taken by A to finish the task = time taken by B – 15

⇒ 2x = 3x – 15

⇒ x = 15

Time taken by A to finish work = 2x = 30 hrs

Then, time is taken by A to do double the work = 2 × 30 = 60 hours.

Time is taken by A to finish double the work is 60 hours.

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