If the standard deviation of Set Y is 4, what are the greatest and least values that are within one standard deviation of the mean?
(1) The median of Set Y is 5.
(2) The mean of Set Y is 6.
standard deviation of Set Y
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Hi j_shreyans,
When a question asks about values that are within a certain number of standard deviations away from a mean, you need to know two things:
1) The standard deviation
2) The mean
In this prompt, we're given the standard deviation (in this case, 4), so we need the mean to figure out what values are within 1 SD of the mean.
Fact 1: The median = 5
This is NOT the mean, so we have no way of answering the question.
Fact 1 is INSUFFICIENT
Fact 2: The mean = 6
This IS the mean, so we CAN answer the question. since the SD is 4, the values within 1 SD of the mean are 2 to 10, inclusive.
Fact 2 is SUFFICIENT
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
When a question asks about values that are within a certain number of standard deviations away from a mean, you need to know two things:
1) The standard deviation
2) The mean
In this prompt, we're given the standard deviation (in this case, 4), so we need the mean to figure out what values are within 1 SD of the mean.
Fact 1: The median = 5
This is NOT the mean, so we have no way of answering the question.
Fact 1 is INSUFFICIENT
Fact 2: The mean = 6
This IS the mean, so we CAN answer the question. since the SD is 4, the values within 1 SD of the mean are 2 to 10, inclusive.
Fact 2 is SUFFICIENT
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
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Let m = the mean of Set Y.j_shreyans wrote:If the standard deviation of Set Y is 4, what are the greatest and least values that are within one standard deviation of the mean?
(1) The median of Set Y is 5.
(2) The mean of Set Y is 6.
Since the SD (standard deviation) of Set Y = 4, we get:
One SD below the mean = m-4.
One SD above the mean = m+4.
Thus:
Any value between m-4 and m+4, inclusive, is within one SD of the mean.
The question stem asks for the values of m-4 and m+4.
To determine these values, we need to know the mean of Set Y.
Question stem, rephrased:
What is the mean of Set Y?
Statement 1: The median of Set Y is 5
INSUFFICIENT.
Statement 2: The mean of Set Y is 6
SUFFICIENT.
The correct answer is B.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
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