Question 1175484
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I'm not sure what you need help with on this, unless you don't understand the vocabulary.<br>
The mean is 23; the standard deviation is 6.6.  One standard deviation below the mean is 23-6.6 = 16.4.<br>
So the question is whether 15 is above or below 16.4.  Above passes; below fails.<br>
Answering the question should be simple.<br>