Bunuel wrote:

Tough and Tricky questions: Work/Rate.

On Sunday morning, a printing press printed its newspapers at a constant rate from 1:00 AM to 4:00 AM. How many newspapers did the printing press print on Sunday morning?

(1) The printing rate on Saturday morning was twice that of Sunday morning.

(2) On Saturday morning, the printing press ran at a constant rate from 1:00 AM to 3:00 AM, stopped for a half hour, and then ran at the same constant rate from 3:30 AM to 5:30 AM, printing a total of 4,000 newspapers.

1) insufficient as we don't know about the rate of printing press on Sunday morning.

2) insufficient as it doesn't provide any information for Sunday morning.

from 2) on Saturday morning the printing press ran for 4hrs (1:00 AM to 3:00 AM + 3:30 AM to 5:30 AM).

This tells us that in 4 hrs the printing press printed 4000 newspapers.

i.e. rate of printing press on Saturday morning : 4000/4=1000 newspapers/hour.

from 1) we know that the printing rate on Saturday morning was twice that of Sunday morning

i.e. rate of printing press on Sunday morning =(rate of printing press on Saturday morning)/2=1000/2=500 newspapers/hour.

As we know from the question stem that the printing press worked for 3hrs(1:00 AM to 4:00 AM) on Sunday morning

Therefore,On Sunday morning the printing press printed : 500*3 = 1500 newspapers. Sufficient.

Answer is C.