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In a certain set the average (arithmetic mean) is known to be 30 and 13 Dec 2016, 07:40
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93% (00:42) correct 7% (00:50) wrong based on 59 sessions

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In a certain set the average (arithmetic mean) is known to be 30 and the standard deviation is known to be 3. Which of the following values is not within 1.5 standard deviations?

A. 20.5
B. 25.5
C. 27.5
D. 30.5
E. 33.5
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A
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In a certain set the average (arithmetic mean) is known to be 30 and 13 Dec 2016, 09:30
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Bunuel
In a certain set the average (arithmetic mean) is known to be 30 and the standard deviation is known to be 3. Which of the following values is not within 1.5 standard deviations?

A. 20.5
B. 25.5
C. 27.5
D. 30.5
E. 33.5

Range = x̅ + 1.5σ

Or, Range = 30 + 1.5*3

Or, Range = 30 + 4.5

Or, Range = 25.5 to 34.5


Thus, except (A) all are within the range of values...
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In a certain set the average (arithmetic mean) is known to be 30 and 13 Dec 2016, 11:17
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hey abhishek how did you calculate would you please explain ?
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In a certain set the average (arithmetic mean) is known to be 30 and 14 Dec 2016, 15:03
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nks2611
hey abhishek how did you calculate would you please explain ?

Hi

Given info =>
Mean = 30
S.D=3

Within 1.5 S.D means the value should be in the bound=> (Mean-1.5*S.D,Mean +1.5*S.D)

Hence The value should be in the bound=> (30-1.5*3,30+1.5*3) => (25.5,34.5)
Now notice the options.
The only value that does not lie in this boundary is 20.5

Hence A

Here is the post that might help you in dealing with everything related to Statistics=> statistics-made-easy-all-in-one-topic-203966.html#p1563159
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In a certain set the average (arithmetic mean) is known to be 30 and 14 Dec 2016, 22:05
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Bunuel
In a certain set the average (arithmetic mean) is known to be 30 and the standard deviation is known to be 3. Which of the following values is not within 1.5 standard deviations?

A. 20.5
B. 25.5
C. 27.5
D. 30.5
E. 33.5

The average is given directly in the qs as 30.

SD is 3 . so limits for 1 SD is 27- 33

but in the sum they ask for 1.5 SD = 3*1.5 = 4.5

so the limits for 1.5 SD is 25.5 - 34.5

Only A is not in limits.
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In a certain set the average (arithmetic mean) is known to be 30 and 16 Dec 2016, 09:45
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Bunuel
In a certain set the average (arithmetic mean) is known to be 30 and the standard deviation is known to be 3. Which of the following values is not within 1.5 standard deviations?

A. 20.5
B. 25.5
C. 27.5
D. 30.5
E. 33.5


Required values will be between= 30+4.5= 34.5 and 30-4.5=25.5
only A is not within the required values of 1.5 standard deviation.
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