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10 Feb 2020, 05:18
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E
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Difficulty:
25%
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Question Stats:
64% (00:52) correct
36%
(00:56)
wrong
based on 172
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What was the standard deviation of Company R's earnings per month for last year?
(1) The standard deviation of Company R's earnings per month in the first half of last year was $2.3 million
(2) The standard deviation of Company R's earnings per month in the second half of last year was $3.9 million
(1) The standard deviation of Company R's earnings per month in the first half of last year was $2.3 million
(2) The standard deviation of Company R's earnings per month in the second half of last year was $3.9 million
10 Feb 2020, 14:32
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Bunuel
The answer is E, because we have no idea what the average was during the first and second halves of the year. The numbers in the question are annoying, so to illustrate I'll use simpler ones. Say the standard deviation of the first six values in a list of twelve things is 1, and the standard deviation of the last six values is 5. Then our list might be:
4, 4, 4, 6, 6, 6, 0, 0, 0, 10, 10, 10
This list won't have a very large standard deviation, because no value is more than 5 away from the mean (which is also 5). But our list might be
4, 4, 4, 6, 6, 6, 1000000, 1000000, 1000000, 1000010, 1000010, 1000010
This list has an enormous standard deviation, because every value in the list is roughly 500,000 away from the mean (which is 500,005). The same principle applies to the question above, so the answer is E.
25 Apr 2020, 04:36
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The answer to this question is E.
> Lets look at the individual statement first.
(1) The standard deviation of Company R's earnings per month in the first half of last year was $2.3 million
The statement 1 is insufficient as it does not give any view of the second half of the year.
(2) The standard deviation of Company R's earnings per month in the second half of last year was $3.9 million
The statement 2 is insufficient with the same reason as statement 1 was insufficient.
> Both statement together.
Statement together doesn't give a view of the individual values of the months from which a mean value could be identified and SD could be calculated further. SO, together insufficient.
Ans (E)
Bunuel : Please guide, if I am wrong in my understanding. I took 3 min to ans this. Could you please give some tips on solving SD DS questions with effective time management.
> Lets look at the individual statement first.
(1) The standard deviation of Company R's earnings per month in the first half of last year was $2.3 million
The statement 1 is insufficient as it does not give any view of the second half of the year.
(2) The standard deviation of Company R's earnings per month in the second half of last year was $3.9 million
The statement 2 is insufficient with the same reason as statement 1 was insufficient.
> Both statement together.
Statement together doesn't give a view of the individual values of the months from which a mean value could be identified and SD could be calculated further. SO, together insufficient.
Ans (E)
Bunuel : Please guide, if I am wrong in my understanding. I took 3 min to ans this. Could you please give some tips on solving SD DS questions with effective time management.
