Carolyn's average vs Jacob's average

[Lakshminarayan]

During a 10 week summer vacation, was the average ( arithmetic mean) number of books that Carolyn read per week greater than the average number of books that Jacob read per week ?

1. Twice the average number of books that Carolyn read per week was greater than 5 less than twice the average number of books that Jacob read per week.

2. During the last 5 weeks of summer vacation, Carolyn read a total of 3 books more than Jacob.

answer is E

the way I solved was

considering statement I alone
let carolyn's average be 'C' and jacob's average is 'J'
then from 1 I have

2C> 2J-5

I plugged in some values for C & J

when C=2 & J=3 C<J so answer is NO

when C=5 & J=4 C>J so answer is YES

so clearly 1 is insufficient

consider statement 2

we don't know the exact value of the average number books read by both on the first 5 weeks so statement 2 is insufficient


Now considering both still the answer can be a 'yes' or 'no'
so neither statement is sufficient to answer the question and the answer is E.

Is the way I solved the best approach or can someone come up with a better way of solving this problem ?

Thanks
Lakshminarayan

[RonPurewal]

what's the source of this problem? remember that this particular folder is for problems from the free GMAT Prep software (from mba.com) only.

it is very unlikely that this problem comes from that source. (e.g., the language of GMAC's problems is always fairly streamlined, and never unnecessarily difficult to interpret; in particular, GMAC would not write that one quantity is "greater than 5 less than" another quantity.)

so,

• please post a thread in the General Math folder, with an explicit citation of the source;

• if this problem really is from the GMAT Prep software, please post a screen shot in this thread.

thanks.

[Lakshminarayan]

Yes Ron the source of the problem is GMAT PREP software. I've attached the URL of the image below please have a look.

http://imageshack.com/a/img537/8801/s2pHtI.png

[RonPurewal]

very interesting. that's not typical of GMAC at all.

is this question in the FREE gmat prep software?
if it's in a paid question pack, we can't use it here.
please clarify, thanks.

[RonPurewal]

in response to the original question:
there's no such thing as "the best solution". if something works, then it works.
if two different things work, then neither of them is "better" than the other.

[Lakshminarayan]

It is from the paid question pack.I apologize for posting a question which is copyright protected. I'll not let this happen again.

Thanks
Lakshminarayan

[RonPurewal]

ok. thanks for being honest. the thread is now locked.