Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
About our questions:
We make every effort to maintain the look, feel, and complexity of the real exam, while respecting all copyright laws and the policies of GMAC.
Add comment May 14th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
About our questions:
We make every effort to maintain the look, feel, and complexity of the real exam, while respecting all copyright laws and the policies of GMAC.
Add comment May 13th, 2008
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
Answer: B
Concepts tested:
1. The standard deviation of a list who’s range is 0 is 0.
2. Standard deviation can only be derived from the numbers in the list, and has nothing to do with the average.
Explanation:
The first statement tells us that Roberta’s average score was higher, but that cannot be enough information because it does not tell us about the dispersion of each of the girls’ scores around the average. Remember that any average number comes from a list of numbers and the standard deviation describes how those numbers are organized in the list. If you were given an average of
200, and a standard deviation of 2, and the numbers would fall in the range of 198-202, or 196-204, depending on the number of standard deviations.
Compare that with an average of 200 and a standard deviation of 15. It’s the same average, but now the numbers are organized much farther way, between 185-215, or 170-230. Based on that, the averages alone cannot describe the list of numbers they come from, and this statement cannot answer the question.
The second statement tells us that the range of Melissa’s test scores was 0. That means there is no dispersion, and thus, her standard deviation must be 0 as well. Since Roberta has a range of 10, there must be some dispersion, so she must have a higher standard deviation than Melissa.
About our questions:
We make every effort to maintain the look, feel, and complexity of the real exam, while respecting all copyright laws and the policies of GMAC.
Add comment May 7th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
Is the standard deviation of Roberta’s 8 test scores higher than the standard deviation of Melissa’s scores on the same 8 tests?
1) Melissa’s average score was 78 and Roberta’s average score was 85.
2) The range of Melissa’s test scores was 0 and the range of Roberta’s test scores was 10.
About our questions:
We make every effort to maintain the look, feel, and complexity of the real exam, while respecting all copyright laws and the policies of GMAC.
Add comment May 6th, 2008
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