Gmat_mission wrote: ↑

Tue Mar 23, 2021 8:11 am

What amount did Jean earn from the commission on her sales in the first half of 1988?

(1) In 1988 Jean's commission was 5 percent of the total amount of her sales.
(2) The number of Jean's sales in the second half of 1988 averaged $10,000 per month more than in the first half.

Answer: E

Source: Official Guide

Target question: What amount did Jean earn from the commission on her sales in the FIRST HALF of 1988 ?

Statement 1: In 1988 Jean's commission was 5 percent of the total amount of her sales.
We don't know her total sales amount in 1988, AND we don't know what happened in the FIRST HALF of 1988
Statement 1 is NOT SUFFICIENT

Statement 2: The amount of Jean's sales in the second half of 1988 averaged $10,000 per month more than in the first half.
We have no information regarding the COMMISSION she receives on sales.
Statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
There are several scenarios that satisfy BOTH statements. Here are two:
Case a: Jean's sales were $0 in the FIRST half of 1988, and $60,000 in the SECOND half of 1988. 5% of $0 = $0. So, the answer to the target question is Jean's commission was $0 in the FIRST half of 19888
Case b: Jean's sales were $60,000 in the FIRST half of 1988, and $120,000 in the SECOND half of 1988. 5% of $60,000 = $3,000. So, the answer to the target question is Jean's commission was $3000 in the FIRST half of 19888
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent