Data Sufficiency

rajatvmittal wrote:16 horses can haul a load of lumber in 24 minutes. 12 horses started hauling a load and after 14 minutes, 12 mules joined the horses. Will it take less than a quarter-hour for all of them together to finish hauling the load?

Mules work more slowly than horses.
48 mules can haul the same load of lumber in 16 minutes.

I'm assuming the read underlined load is same as the one in blue. Otherwise, answer is definitely going to be E.

The question is asking whether all of them together will finish hauling the load in 15 minutes or not. To answer this we need to know the work capacity of the mules.

16 horses in 24 minutes --> Finish hauling the complete load
1 horse in 1 minute ------> Finish hauling 1/(16*24) of the load

Statement 1: Even if 24 horses were hauling the load, in 15 minutes they will finish hauling 24*15/(16*24) = 15/16 of the load, i.e. 24 horses will not be able to finish hauling the load in 15 minutes.

As mules work more slowly than horse, 12 mules and 12 horses definitely won't finish hauling the load in 15 minutes.

Sufficient

Statement 2: Now we can uniquely determine the work capacity of the mules. Hence, we can definitely answer the question in YES or NO.

Sufficient

The correct answer is D.