sample data

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ST: Master | Next Rank: 500 Posts; Posts: 191; Joined: Sat Feb 14, 2009 11:56 am; Thanked: 1 times

by ST » Thu Jun 04, 2009 11:30 am

If a certain sample of data has a mean of 20.0 and a standard deviation of 3.0 which of the following values is more than 2.5 standard deviation from the mean?

a. 12.0
b. 13.5
c. 17.0
d. 23.5
e. 26.5

Answer is A

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Source: Beat The GMAT — Problem Solving | Thu Jun 04, 2009 11:30 am

SanjeevK: Senior | Next Rank: 100 Posts; Posts: 89; Joined: Sat May 30, 2009 2:49 am; Thanked: 9 times

by SanjeevK » Thu Jun 04, 2009 11:48 am

Mean = 20.
SD = 3. So 2.5 SD = 7.5

Values with mean = 3 and SD = 7.5 will lie between (20-7.5) and (20+7.5)

IMO: A

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