Sunil01 wrote:

IS A multiple of 6 ?

1) A = B(B+4)(B-4)

2) B-4 is a multiple of 3

Target question: Is A multiple of 6 ? Given: If the average (arithmetic mean) the 4 numbers is 30 Statement 1: A = B(B+4)(B-4) Since we're not told whether or not A and B are integers, this one seems insufficient.

If B = 6 then we have A = (6)(something)(something) and this means

A is definitely divisible by 6.

However, if B = 1.4993949349394994, I know right away that A is not even an integer, which means

A is definitely NOT divisible by 6.

Since we cannot answer the

target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: B-4 is a multiple of 3 Since there's no related information about A, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined Test some values of B that satisfy statement 2. Here are two:

Case a: B = 7, in which case A = 7(7+4)(7-4) = (7)(11)(3) = some ODD integer. Here, we can see that

A is NOT divisible by 6Case b: B = 10, in which case A = 10(10+4)(10-4) = (10)(14)(6). Here, we can see that

A IS divisible by 6Since we cannot answer the

target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

Cheers,

Brent

_________________

Brent Hanneson – Founder of gmatprepnow.com

Brent also tutors students for the GMAT