Bunuel wrote:

The 10 students in a history class recently took an examination. What was the maximum score on the examination?

(1) The mean of the scores was 75.

(2) The standard deviation of the scores was 5.

NEW question from GMAT® Official Guide 2019

(DS02939)

As the question stem doesn't make it clear where to start, we'll first try a few examples.

This is an Alternative approach.

(1) OK, but how much is the maximum? Could be 80, 85, 90, anything above the mean.

Insufficient.

(2) Still no useful information.... though finding specific examples is time consuming (as the equation for std is involved), we can think of the std as an expression with 10 variables representing the 10 different scores. So the maximum could, as above, be any number, such as 50, 30, 90, etc...

Insufficient.

Combined: Still not helpful, as we now have two equations for 10 variables (our 10 scores): std = 5 and mean = 75. So we cannot solve.

(E) is our answer.

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