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The question given below is a problem solving question focusing on relative efficiencies from the topic Work and Time.

Ram, who is half as efficient as Krish, will take 24 days to complete a work if he worked alone. If Ram and Krish worked together, how long will they take to complete the work?

1. 16 days
2. 12 days
3. 8 days
4. 6 days
5. 18 days

The correct choice is (C) and the correct answer is 8 days.

Ram takes 24 days to complete the work, if he works alone.
As Krish is twice as efficient as Ram is, Krish will take half the time to complete the work when Krish works alone, i.e., in 12 days.

Ram completes th of the work in a day.
Krish completes th of the work in a day.
When they work together, they will complete th work in a day.
Therefore, when they work together they will complete the work in 8 days.