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

Question

Over a seven-week period a company monitored the output of two of its factories, C and D. Each week the company calculated how many units were produced in each factory. The factory that produced the greatest number of units for four or more of the seven weeks was considered the more efficient factory. Which factory was deemed the more efficient?

(1) Over the seven-week period factory C produced twice as many units as factory D.

(2) The factory that was more efficient was known by the fifth week.

(1) Over the seven-week period factory C produced twice as many units as factory D.

(2) The factory that was more efficient was known by the fifth week.

Bunuel · Accepted Answer

Too many words...

Consider two cases:

C = { 0, 1, 1, 1, 1,  0, 0}
D = { 0, 0, 0, 0, 0,  2, 0}

C = { 0, 0, 0, 0, 0,  8, 0}
D = { 0, 1, 1, 1, 1,  0, 0}

Answer: E.

vibhav · Answer

The main catch in this question is that it is no where mentioned that the factories have a constant rate of production or the maximum units each production each facility can deliver in a day. Thus,

Stmnt 1: says c produced 2x units and D produced x units. Now it is possible that D produced more units for than C for 6 weeks but in the 7th week C ran at full production capacity and beat D's total production for 7 weeks and delivered a total of 2x units.

Stmnt 2: By itself cannot say which factory was more efficient.

Combined, again we know nothing because of the variability of production as seen through statement 1.

jlgdr · Answer

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

gmatkum · Answer

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.

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

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

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Data Sufficiency (DS) Questions

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

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards