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GRE Statistics http://www.800score.com/forum/viewtopic.php?f=12&t=15286 
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Author:  questioner [ Tue Dec 18, 2012 8:26 am ] 
Post subject:  GRE Statistics 
Given the two lists: List 1: 7, 8, 12, 15 List 2: 2, 10, 10, 13, 18 Indicate ALL correct answers. The mean of List 1 > The mean of List 2 The median of List 1 > The mode of List 2 The standard deviation of List 1 > The standard deviation of List 2 The range of List 1 > The range of List 2 None of these is true.  The correct answer is None of these is true. First, remember the definitions. Mean (average) – sum of all elements of a set divided by the number of the elements. Median – if the number of the elements in a set is odd, then it is the middle number of the set arranged in ascending or descending order; if the number of the elements in the set is even, then it is the average of the two numbers in the middle of the arranged set. Mode – the element(s) that appears most frequently. Range – The largest element minus the smallest. Let's look at each choice. Choice A: the mean of List 1 is (7 + 8 + 12 + 15)/4 = 42/4 = 10.5, and the mean of List 2 is (2 + 10 + 10 + 13 + 18)/5 = 53/5 = 10.6. False. Choice B: The median of List 1 is (8 + 12)/2 = 10, and the mode of List 2 is 10. False. Choice C: It is not necessary to calculate the standard deviation. Just note that the data are much more spread about List 2, so its standard deviation is greater. False. Choice D: The range of List 1 is (15 – 7) = 8 and the range of List 2 = (18 – 2) = 16. False. All of the first 4 answer choices are false. Therefore, Choice E, none of these is true, is correct.  The median of List 1 is 11. 
Author:  Gennadiy [ Tue Dec 18, 2012 8:34 am ] 
Post subject:  Re: GRE Statistics 
Quote: The median of List 1 is 11. The median of List 1 is 10List 1: 7, 8, 12, 15 Median – if the number of the elements in a set is odd, then it is the middle number of the set arranged in ascending or descending order; if the number of the elements in the set is even, then it is the average of the two numbers in the middle of the arranged set. List 1 is arranged in the ascending order and has four elements, which is an even number. Therefore the median is the average of the two middle numbers, 8 and 12. (8 + 12) / 2 = 10 P.S. The median outside of the high school mathematics can be defined in a different way, but in GMAT we use only the definition provided above. 
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