Over a seven-week period a company monitored the output of t

So the question is really telling us that for a factory to be the most efficient then it must the case that it produces the greatest number of units for 4 or more weeks. Let's see.

Statement 1 tells us that over the 7 weeks factory C produced twice as many. But this doesn't tell us whether it did so for at least 4 weeks so this is insufficient.

Statement 2 tells us that the more efficient was known by the fifth week but still insufficient because we don't know which is which. Both together, we know that at the end of the period C produced twice as many but D could have been the most efficient and C could in fact have produced more then double the amount during the last week, we actually have no constraints here or whatsoever so the answer is clearly E.

Hope this helps
Cheers
J

Statement 1) this statement says that factory C produced twice as many units in total over the span of seven weeks. This doesn't tell us whether 4 or more of those weeks had levels above those at plant D.

Think about two simple scenarios,
Plant C produces 0 units in weeks 1-6 and 14,000 units in week 7. Total units = 14,000.
Plant D produces 1,000 units in each week. Total units = 7,000.

In this case, plant D produces more units in 6 out of 7 weeks, and is the more efficient plant.

The other scenario is that plant C produces 2,000 units per week and D produces 1,000 units per week. In this case plant D is the more efficient plant.

Insufficient.

Statement 2) The statement says nothing about the distribution of units produced for either plant. Insufficient.

Combined) After adding the second statement to the first, both scenarios I listed are still possible, and still yield different results for the more efficient plant. Insufficient. Hence E.

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.