Anyone please explain, how "B" can be the answer?

(1) is clearly insufficient

(2) Between 9:00 a.m. and 10:40 a.m 1/3 of the work was done.

This means that in 100min 1/3 of the work is done. Using \(Rate = \frac{work}{time}\) we get Rate as 1/300 work/min. Or 1/5 work/hr

Now what do we mean by Rate = 1/5th? It means that 1/5th of the total work was done in 1 hr. So we can say that 1 entire Unit of work is done in 5hrs.

Learning
1. Time is inversely proportional to work
2. Work is inversely proportional to time

Keeping the above in mind we could also say that since rate is 1/5 time is 5

Note This is a DS question. You don't need to solve the question all the way through. Once you realse that the Rate cab be found from (2) we can conclude that (2) is sufficient to answer.

Correct Answer: (B)

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