What is approximate standard deviation for the list of

numbers: 10.4, 9.8, 10.0, 9.2, 10.5, 9.8, 9.9, 10.1,

10.4, 10.2, 10.7, 9.6?

A. 2.1 B. 1.9 C. 1.75 D. 1.8

The question shows up on my kid's test recently.

The standard deviation is 0.42. Why can the answer be C.


If 0.42 is the correct standard deviation, the answer

choice 1.75 is TOO LARGE to be called an "approximate",

so there is not a valid or or reasonable answer. So, the

question is not valid and should be excluded from the

test score.

Anyone agreee? Please correct me if my thoughts are



1 Answer 1


I think you're exactly right. None of those answers are really even close to the actual standard deviation.

Choice C is the closest of the four, but it's still way off.

  • $\begingroup$ Truly weird. Answers (c) and (d) are only 0.05 apart yet (c) is 1.33 from the right answer - and the kid is supposed to be approximating !?! $\endgroup$
    – MaxW
    Sep 9, 2016 at 21:40

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