Took GMATPrep CAT Practice Test 1 today. Scored a 710 which I was surprised because of how many problems I missed. I missed 9 in Quant and 9 in Verbal. Projection was a 49 Quant and 38 Verbal. I have heard that people say that this test is most accurate. I have been scoring about a 680 on the

Kaplan tests. I missed 5 in a row in quant and still got a 710!!! I just can't actually believe that they would let me get away with that. If anyone can verify that these projections are relatively semi-accurate, that would really calm my nerves.

Anyways, I found this problem and, although I have found the solution, I am sure that the steps I took to get there are not the most efficient. Here is the problem.

Data Sufficiency-

If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 23, what is the value of R?

1. n is not divisible by 2

2. n is not divisible by 3

My Solution: I finally found that the numbers that are not div by 2&3 end up being prime or prime multiples of primes. Then, I finally realized though trial and error that all numbers surrounding the primes (i.e n+1 & n-1) are divisible by 2x2x2x3 (24). I have no clue why this phenomenon works and really don't care to. Is there some way to approach a problem of this nature more efficiently?

I also struggled with this one...

Q: If n and y are both positive integers and 450y=n^3, which of following MUST be an integer?

I. y/(3x2x2x5)

II. y/(3x3x2x5)

III. y/(3x2x5x5)

I missed this and still don't know how to solve. Apparently the answer is Only "I" but I don't know why.

Thanks.

-Anthony

PS: If this is posted in the wrong place... please let me know. It's my first post.