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For a group of test-takers, the scores on an aptitude test w

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For a group of test-takers, the scores on an aptitude test w [#permalink] New post 17 Sep 2017, 11:53
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For a group of test-takers, the scores on an aptitude test were normally distributed, had a mean of 154, and a standard deviation of 3.

Quantity A
Quantity B
The fraction of test-takers in the group who
scored greater than 158
\(\frac{1}{3}\)


A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
[Reveal] Spoiler: OA

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Re: For a group of test-takers, the scores on an aptitude test w [#permalink] New post 17 Sep 2017, 23:26
Is this based on the fact that each half of the normal distribution contains 0.5 probability and that the probability between the mean and 1sd, 2sd and 3sd is known to be, respectively, 0.34, 0.136 and 0,023? Thus, given that 158 is a number more than 1sd from the mean, the probability of lying there should be equal to 0.136+0.023=0.158 so less than 1/3 that is roughly 0.333. Thus, answer is B.
Re: For a group of test-takers, the scores on an aptitude test w   [#permalink] 17 Sep 2017, 23:26
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For a group of test-takers, the scores on an aptitude test w

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