Last August the XT chain

[BrandenF768]

Last August the XT chain of gasoline stations had a temporary sales promotion in effect. In the promotion, any customer who made a purchase of ten or more gallons of gasoline was entitled to a free car wash. For the month of August, XT experienced a ten percent increase in gasoline sales as compared to sales in August the previous year. So evidently the promotion was successful as a means of boosting sales.

In evaluating the argument, it would be most helpful to answer which of the following?

A. In the areas in which XT’s gasoline stations operate, how did total combined gasoline sales for all gasoline stations last August compare with sales for the previous August?
B. Was the money that XT earned from the increase in gasoline sales enough to offset the cost of providing free car washes during the promotion?
C. Were there any customers who bought ten or more gallons at an XT gasoline station during the promotion who would have bought gasoline at the same station in lower quantities, but more frequently, if the promotion had not been in effect?
D. Did XT or any of its gasoline stations have to pay other businesses to provide the car washes that customers were offered in the promotion?
E. Are XT’s gasoline sales in August usually significantly higher than one twelfth of XT’s annual gasoline sales?

[End of question - apologies if this question is already in the forum...the only instance I saw was an incorrectly copied version]

For me, it came down to answer choices A and C. Before even looking at the answer choices, I predicted that the correct answer choice would maybe provide insight into an alternative cause to the boost in sales. We've got two events in the argument: 1) sales promotion, and 2) boost in sales. So immediately I think causal reasoning.

Ultimately I chose C, which was incorrect. I don't understand how A provides any additional information that the argument doesn't already provide, as the argument states that sales for XT was 10% greater in August last year than in the previous year. How does A help evaluate the argument further? The argument already tells us how the two Augusts' sales compare!

Thanks in advance.

[RonPurewal]

ok, so, first, you understand what the ISSUE is, right?

the ISSUE in the problem is that we don't know whether the PROMOTION is responsible for the increase in sales.
you see that, right?
the increase in sales COULD have come from any number of other things, too. (for instance, say there was a really big political convention in town THIS august... but not last august.)

that's what we have to decide.

__

I don't understand how A provides any additional information that the argument doesn't already provide, as the argument states that sales for XT was 10% greater in August last year than in the previous year.

the red part ^^ suggests that you've read choice A incorrectly—most likely as a result of reading too fast. slow down!

here's the text of choice A:
In the areas in which XT’s gasoline stations operate, how did total combined gasoline sales for all gasoline stations last August compare with sales for the previous August?

notice the blue thing.
that's the sales for ALL gas stations—NOT just the XT stations.

the point is that the OTHER stations AREN'T running this promotion.
so, if the blue statistic increased in the same way as XT's statistic, then, it's a safe bet that the promotion really didn't have anything to do with the increased sales (and that something else, e.g., a special event in town, was responsible instead).

[BrandenF768]

Yep I just read it wrong in the way you described. That was my issue. Once read correctly it became straightforward.

[RonPurewal]

excellent.

[HariR842]

How about E? I thought if the August sales is generally highest for the annual sales of gasoline at XT, then sales surge last August has got nothing to do with the promotion. However, if the sales in August isn't usually significantly higher, then it strengthens the argument that the sales boost was indeed from the promotion.

[RonPurewal]

whether august is generally better (or worse) than other months of the year is irrelevant here, since we are trying to justify why THIS AUGUST had better sales numbers than LAST AUGUST.

we're not talking about august vs. other months.

[YANFEIG811]

I think both A and C are correct.

C: if the answer is yes, then it means that due to the promotion, people who would have bought more gallons at an XT gasoline in lower quantities but in higher frequency bought 10 or more gallons in Aug at XT gasoline station. Essentially, promotion changed the customer behavior which changed the sales in Aug.

What is wrong with my understanding?

[RonPurewal]

"lower quantities, but higher frequency" could be more than, less than, or the same amount as the customers purchased during the promotion.
it's impossible to tell. therefore, it's impossible to tell what effect -- if any -- this would have on the argument.

[YANFEIG811]

"lower quantities, but higher frequency" could be more than, less than, or the same amount as the customers purchased during the promotion.
it's impossible to tell. therefore, it's impossible to tell what effect -- if any -- this would have on the argument.

Just saw your reply. Got it, thanks a lot! I made the mistake of assuming that the high frequency multiply the lower quantities = low frequency multiply the higher quantities (which is led by the promotion).

[RonPurewal]

hm, yeah—watch those assumptions.

[PeruguN429]

Regarding Option A:

Assume Total combined sales increased :
Scenario1: Only XT chain's sales increased and sales of other companies remained same . This anyways increase the total sales.

Conclusion1: Promotion was responsibel for the increase in the sales.

Scenario 2: Sales of all the companies increased . Total sales will again increase .

Conclusion : Promotion was not likely to be responsible for the increase in sales.

These two contradictory conclusion forced me not to choose A.

[Sage Pearce-Higgins]

Forced you not to choose A?! This reasoning (if I understand it correctly) means that you should choose A.

When we're solving an evaluate problem, we can test the answers by thinking "What would be the case if we had an answer to this question?". Remember that 'evaluate' means 'say if the argument is good or not'. As you describe, if other companies reported a similar increase in gasoline sales, then the increase at XT was likely to be due to some other factor, and the promotion wasn't responsible. Alternatively, if other companies didn't report an increase in sales, then it's likely that the promotion was the reason that sales increased. This means that answer A is useful in evaluating the argument.

Perhaps you're confusing yourself by thinking of two 'conclusions'. I encourage you to save that word for the conclusion in the argument. It looks like you've correctly identified it as 'the promotion was successful as a means of boosting sales'. Our job is to think 'If I got an answer to the question posed in A, what would the conclusion in the argument be strengthened or weakened?'.