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04 Jun 2019, 00:32
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D
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Difficulty:
15%
(low)
Question Stats:
78% (00:32) correct
22%
(00:49)
wrong
based on 97
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A list of numbers has a mean of 8 and a standard deviation of 2.5. If x is a number in the list that is 2 standard deviations above the mean, what is the value of x ?
A. 10
B. 11
C. 12
D. 13
E. 14
A. 10
B. 11
C. 12
D. 13
E. 14
04 Jun 2019, 07:00
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Bunuel
---------ASIDE----------------------------
A little extra background on standard deviations above and below the mean
If, for example, a set has a standard deviation of 4, then:
1 standard deviation = 4
2 standard deviations = 8
3 standard deviations = 12
1.5 standard deviations = 6
0.25 standard deviations = 1
etc
So, if the mean of a set is 9, and the standard deviation is 4, then:
2 standard deviations ABOVE the mean = 17 [since 9 + 2(4) = 17]
1.5 standard deviations BELOW the mean = 3 [since 9 - 1.5(4) = 3]
3 standard deviations ABOVE the mean = 21 [since 9 + 3(4) = 21]
etc.
-------------------------------------------
A list of numbers has a mean of 8 and a standard deviation of 2.5. If x is a number in the list that is 2 standard deviations above the mean, what is the value of x ?
x = 8 + 2(2.5)
= 8 + 5
= 13
Answer: D
Cheers,
Brent
General Discussion
04 Jun 2019, 01:52
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Bunuel
value = 8+2*2.5
13
IMO D
