Set S consists of N elements. If N>2 what is the standard deviation of S?
1) The mean and the median of the set are equal.
2) The difference between any two elements is equal.
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Set S consists of N elements
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saketk
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Statement 1: -- {1,2,3,4,5} -- mean and median equalamsm25 wrote:Set S consists of N elements. If N>2 what is the standard deviation of S?
1) The mean and the median of the set are equal.
2) The difference between any two elements is equal.
Also, {3,3,3,3,3,3} -- Mean and median equal ..
BUT, the SD in both cases is different.. Hence STATEMENT 1 is insufficient.
Statement 2: The difference between any two elements can only be equal when all the elements are same
{1,1,1,1,1,1} or {2,2,2} etc.. Clearly, in each case SD is ZERO.
Hence, STATEMENT 2 is SUFFICIENT.
ANSWER B
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samyukta
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ST 1 : Mean is equal to median which means set has equally spaced elements.
It can be like : 1,2,3,4 or 2,4,6,8. Now both will have different SD.
Insufficient
ST 2: Difference between the elements should be same.... It means all elements are same.
So SD will be zero!!
Pick B
It can be like : 1,2,3,4 or 2,4,6,8. Now both will have different SD.
Insufficient
ST 2: Difference between the elements should be same.... It means all elements are same.
So SD will be zero!!
Pick B
Had the second statement been //2) The difference between every two elements is equal.// would the answer have been E?
Because both statements would suggest that we are grappling with an evenly spaced set, of which we ignore the number of elements.
Am I right?
Because both statements would suggest that we are grappling with an evenly spaced set, of which we ignore the number of elements.
Am I right?
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Brent@GMATPrepNow
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Your wording "The difference between every two elements is equal" is virtually the same as the original "the difference between any two elements is equal."wolfmarc wrote:Had the second statement been //2) The difference between every two elements is equal.// would the answer have been E?
Because both statements would suggest that we are grappling with an evenly spaced set, of which we ignore the number of elements.
Am I right?
If the question stated that the elements (numbers) in set S are arranged in ASCENDING order, and statement 2 was "The difference between any two ADJACENT elements is equal," then the answer would be E
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Brent
Brent Hanneson - Creator of GMATPrepNow.com
