Finding of a survey of Systems magazine subscribers:

[viest]

Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five.

Finding of a survey of advertisers in Systems magazine: Most of the merchandise orders placed in response to advertisements in Systems last year were placed by people under age thirty-five.

For both of the findings to be accurate, which of the following must be true?

(A) More subscribers to Systems who have never ordered merchandise in response to advertisements in the magazine are age thirty-five or over than are under age thirty-five.
(B) Among subscribers to Systems, the proportion who are under age thirty-five was considerably lower last year than it is now.
(C) Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five.
(D) Last year, the average dollar amount of merchandise orders placed was less for subscribers under age thirty-five than for those age thirty-five or over.
(E) Last year many people who placed orders for merchandise in response to advertisements in Systems were not subscribers to the magazine.
OA is E.
Could you help me this question?

[RonPurewal]

this problem features QUANTITATIVE DATA. that may make you grimace, depending on your mindset about quantitative data, but it shouldn't: all you need to do is look for the discrepancy in the numbers, and then find an answer choice that accounts for the discrepancy. unlike problems that are all words, these problems feature discrepancies that will essentially jump out at you if you examine the numbers.

when you examine the numbers, you must also pay close attention to DIFFERENCES, especially SLIGHT categorical differences, between categories that are being compared. in this problem, the most important difference is between subscribers who order and people who order. (there's also the distinction between random orders and orders in response to ads, but that distinction isn't tested, because both surveys are on the same side of it.)

in this problem:
of the orders placed by subscribers in response to ads, only 30% were from the under-35 crowd.
of the orders placed by anyone in response to ads, over 50% were from the under-35 crowd.
there's the discrepancy.

therefore, you need an answer choice that explains where all the extra orders in the 'anyone' category came from. this means in the 'anyone' category and not in the 'subscribers' category; no more, no less. that's exactly what is described in choice e.

bam!

[puneet.sharma]

this problem features QUANTITATIVE DATA. that may make you grimace, depending on your mindset about quantitative data, but it shouldn't: all you need to do is look for the discrepancy in the numbers, and then find an answer choice that accounts for the discrepancy. unlike problems that are all words, these problems feature discrepancies that will essentially jump out at you if you examine the numbers.

when you examine the numbers, you must also pay close attention to DIFFERENCES, especially SLIGHT categorical differences, between categories that are being compared. in this problem, the most important difference is between subscribers who order and people who order. (there's also the distinction between random orders and orders in response to ads, but that distinction isn't tested, because both surveys are on the same side of it.)

in this problem:
of the orders placed by subscribers in response to ads, only 30% were from the under-35 crowd.
of the orders placed by anyone in response to ads, over 50% were from the under-35 crowd.
there's the discrepancy.

therefore, you need an answer choice that explains where all the extra orders in the 'anyone' category came from. this means in the 'anyone' category and not in the 'subscribers' category; no more, no less. that's exactly what is described in choice e.

bam!

That was really a great help Ron
people like you are badly needed to fight this GMAT WAR

i often get my head spinning with these kind of problems
i will try to use your approach for these kind of questions

[tim]

:)

[prashant.ranjan]

Figured out a quantitative view of anlaysing the situation. In any way. Just an approach to make things more clear (In any way, RON's method is the best).


One way to solve this problem is to construct a table:

-----------------Less than 35------>=35 (Age)-----------Total
Subscribers--------30% X-------------70% X---------------X
Non-subscribers---->=21--------------<=42----------------Y
Total reqd to be----->=51-------------<=49---------------100

Let us suppose that the total number of people surveyed were 100. Consider that those who were subscribers are X and those who are Non subscribers as Y. Now if we suppose that there were no non-subscribers surveyed then it means that Y=0 and the number of people surveyed i.e. 100 of them were subscribers. Thus the table becomes:
"ƒ
--------------Less than 35-------->=35 (Age)--------Total
Subscribers---------30------------------70------------100
Non-subscribers-----0-------------------0--------------0
Total reqd to be--->=51--------------<=49------------100

However if this were true, as you can see in the table it contradicts the premise of the passage that Most of the people surveyed were less than the age of 35. For this purpose we can conclude that there must surely have been people who did not belong to the subscribers category in addition to account for that extra number. Thus we come at the minimum number of people who were non-subscribers and surveyed and less than the age of 35 to be 21.

-----------------Less than 35------>=35 (Age)-----------Total
Subscribers--------30% X-------------70% X---------------X
Non-subscribers---->=21--------------<=42----------------Y
Total reqd to be----->=51-------------<=49---------------100

In the same way the minimum number of people who might be surveyed and were more than the age of 35 should be 7 (a whole number) and in that case the number of non-subscribers should be of maximum number 42 or less than that.
Consider any case and the numbers would satisfy the equations as mentioned in the table (the condition is that the numbers should be of whole value and hence considered in multiples of 10<100).

Thanks
Prashant

[RonPurewal]

ok fine, prashant. but, if you actually have to pick explicit numbers on a problem like this, then what that means is that, on some level, you lack the intuition that the problem is actually trying to test. quantitative CR problems aren't meant to test specific numbers; they're meant to test the MEANING and INTUITION behind very general numerical ideas.

note my post above -- the only explicit math you need here is the fact that "30%" is less than "over 50%".

[prashant.ranjan]

Reading the same replies of Ron and mine after 4 months!! and I know why people say Ron is the best !!

Thanks
Prashant
------------
Big fan : )

[tim]

:)

[amysky_0205]

I want to know why D is wrong.
thank u :)))

[tim]

what makes you think D is right? and more importantly, what makes you think it is MORE right than the OA? if you can't answer both of these questions, THAT'S what makes D wrong..

[mcmebk]

this problem features QUANTITATIVE DATA. that may make you grimace, depending on your mindset about quantitative data, but it shouldn't: all you need to do is look for the discrepancy in the numbers, and then find an answer choice that accounts for the discrepancy. unlike problems that are all words, these problems feature discrepancies that will essentially jump out at you if you examine the numbers.

when you examine the numbers, you must also pay close attention to DIFFERENCES, especially SLIGHT categorical differences, between categories that are being compared. in this problem, the most important difference is between subscribers who order and people who order. (there's also the distinction between random orders and orders in response to ads, but that distinction isn't tested, because both surveys are on the same side of it.)

in this problem:
of the orders placed by subscribers in response to ads, only 30% were from the under-35 crowd.
of the orders placed by anyone in response to ads, over 50% were from the under-35 crowd.
there's the discrepancy.

therefore, you need an answer choice that explains where all the extra orders in the 'anyone' category came from. this means in the 'anyone' category and not in the 'subscribers' category; no more, no less. that's exactly what is described in choice e.

bam!

Hi Ron

Sorry I am really confused at this question.

What do you mean "explains where all the extra orders in the 'anyone' category", using the number you gave in the post below, people under age 35 is 51% of the "Anyone category (Group A)", so the people who are non subscribers are A-S - How do define the relationship between A and S?

Is it because: there are 70% of subscribes from people above age 35%, but the 70%*S only comprises of 49%*A, so A is substantially greater than S?

Thanks.

[RonPurewal]

ok, there are way too many unnecessary numbers floating around here. (If you are "plugging in numbers" on CR questions, then that means you should probably be thinking a little more about what the numbers mean; remember, people, this isn't the quant section.)

let's just use an analogy instead.
* Only 30% of the women in this room are wearing glasses.
but...
* More than half of all the people in this room are wearing glasses.

ok. when you look at those two statements together, hopefully, you should be able to see, without having to calculate things, that the room has to contain a significant # of men wearing glasses. right?

ok, now make the analogy:
wearing glasses --> ordered merchandise
women --> subscribers
men --> non-subscribers

there you go.

[momo32]

Dear Ron，

I want to ask why c is wrong？
Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five.
We can infer this choice from Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five.

Do i focus on a wrong perspective? and should i focus on the discrepancy?

THX

[RonPurewal]

Dear Ron，

I want to ask why c is wrong？
Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five.
We can infer this choice from Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five.

Do i focus on a wrong perspective? and should i focus on the discrepancy?

THX

The "finding" is limited to subscribers' orders. Take a look at the pink-colored text.

Choice C, on the other hand, attempts to generalize to ALL orders, not just subscribers' orders. Green text.
If most people who place orders are non-subscribers, then choice C will be wrong.

[aidenk363]

------------------| Less than 35 |--| >=35 (Age) |-- |Total|
Subscribers-----|_____3______|--|_____7____|-- | 10 |
Nonsubscribers-|_____5______|--|_____0____|-- | 5 |

This case satisfies with above mentioned two facts that it doesn't indicate ans "E" must be true.
can anyone help with this?