Data Sufficiency

kwah wrote:Attached is a question from GMAT Prep Test 2.

Please advise how to achieve the result.

Answer: E

Thanks,
K

Let us assume that T = total no. of boxes packed
and let Linda, Robert, and Pat packed L, R, and P boxes respectively.
L + R + P = T

(1) Linda packed 30% of the total number of boxes of books.
L = 30% of T
L = 0.30T; NOT sufficient.

(2) Robert packed 10 more boxes of books than Pat did.
R = 10 + P; NOT sufficient.

Combining (1) and (2), L + R + P = T, L = 0.3T and R = 10 + P, but still we cannot find R : P usinf these equations; NOT sufficient.

The correct answer is E.