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Arithmetic mean and standard deviation of a certain normal

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anilnandyala
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Arithmetic mean and standard deviation of a certain normal [#permalink] New post   Updated on: 19 Feb 2012, 22:25
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Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 1.5. What value is exactly 2 standard deviations less than the mean?
(A) 10.5
(B) 11
(C) 11.5
(D) 12
(E) 12.5
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A

Originally posted by anilnandyala on 02 Nov 2010, 05:32.
Last edited by Bunuel on 19 Feb 2012, 22:25, edited 1 time in total.
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Re: the arthimetic and standard deviation [#permalink] New post   02 Nov 2010, 05:49
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Original question is:

Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 1.5. What value is exactly 2 standard deviations less than the mean?
(A) 10.5
(B) 11
(C) 11.5
(D) 12
(E) 12.5

The value which is exactly two SD below the mean is: mean-2*SD=13.5-2*1.5=10.5.

Answer: A.
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Fijisurf
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Re: the arthimetic and standard deviation [#permalink] New post   02 Nov 2010, 14:32
Is this question really a 600-700 level?
What is the source?
Thanks
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Re: Arithmetic mean and standard deviation of a certain normal [#permalink] New post   05 Jan 2021, 13:20
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anilnandyala wrote:
Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 1.5. What value is exactly 2 standard deviations less than the mean?
(A) 10.5
(B) 11
(C) 11.5
(D) 12
(E) 12.5



MEAN -2SD=13.5-2*1.5=13.5-3=10.5

The answer is A
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Re: Arithmetic mean and standard deviation of a certain normal [#permalink] New post   29 May 2023, 01:33
To find the value that is exactly 2 standard deviations less than the mean, we need to subtract 2 times the standard deviation from the mean.

Given that the mean is 13.5 and the standard deviation is 1.5, we can calculate:

Value = Mean - (2 * Standard Deviation)
Value = 13.5 - (2 * 1.5)
Value = 13.5 - 3
Value = 10.5

Therefore, the value that is exactly 2 standard deviations less than the mean is 10.5.

So, the answer is (A) 10.5.
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Re: Arithmetic mean and standard deviation of a certain normal [#permalink]
29 May 2023, 01:33
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