GRE Math Problem 11

Given: x<y
Compare two values:

Column A	Column B
The average (arithmetic mean) of x and y	The average (arithmetic mean) of x, y, and y

Solution for GRE Math Problem 10:

In 1990 for twice less money we could buy twice more potatoes. So, the cost became 2x2=4 times less than in 1980. So, the price in 1990 was a quarter or 25% of the price in 1980. But the question is “By what percent did the price of potatoes decrease from 1980 to 1990?” Assuming price in 1980 as 100%, we get 100%–25%=75%
Answer:C

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