OG DS #91

[angiekara]

By what percent did the median household income in Country Y decrease from 1970 to 1980?

(1) In 1970 the median household income in Country Y was 2/3 of the median household income in Country X.
(2) In 1980 the median household income in Country Y was 1/2 of the median household income in Country X.

(A) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
(B) Statement (2) ALONE is sufficient, but statement (2) alone is not sufficient.
(C) BOTH statements together are sufficient, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient.
(E) Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed.

The correct answer is (E)

The explanation says, there is no explicit information about the household income of Country X or Country Y. And I agree. But my question is - if we add the information (the household income in Country X was same in 1970 and in 1980).

Then can the answer be (C)?

Please help!!

GMAT 2007

[Kishore]

The problem could be solved if the additional information that the household income of country x remained the same is provided.

Because then:

Let the house hold income of country X be $1.
Then Household income of country Y in 1970 and 1980 are $ 2/3 and $ 1/2 respectively (Using information in both 1 and 2)

Then percentage decrease = [(2/3) - (1/2)]/(2/3) * 100 = 25%

Hope this helps.

-- Kishore

[StaceyKoprince]

Yep, Kishore's right!