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GMATPrep Test 1 : PS #32

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by kaizenwerks » Wed Oct 31, 2007 7:59 pm
Happy Halloween everyone,

Could someone explain the answer on this one?

The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

30
20
18
12
6


Thanks!
Best regards,

GMAT monkey
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by naren_nayak » Wed Oct 31, 2007 8:05 pm
Since std dev = 6 => 1 std dev = 6, 2 std dev = 12.
1 std dev below the mean (which is 21) is 21-6 = 15 hours
2 std dev below the mean = 21 - 12 = 9 hours
Time Pat watched TV is between 9 and 15 hours. 12 is the only answer that falls in this range. Hence D.
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Newbie | Next Rank: 10 Posts
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Thanks naren_nayak!

by kaizenwerks » Wed Oct 31, 2007 8:38 pm
That makes perfect sense.
Best regards,

GMAT monkey
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