800score.comhttp://www.800score.com/forum/ GRE Statisticshttp://www.800score.com/forum/viewtopic.php?f=12&t=15286 Page 1 of 1

 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, 18Indicate ALL correct answers.The mean of List 1 > The mean of List 2The median of List 1 > The mode of List 2The standard deviation of List 1 > The standard deviation of List 2The range of List 1 > The range of List 2None 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, 15Median – 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 = 10P.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.

 Page 1 of 1 All times are UTC - 5 hours [ DST ] Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Grouphttp://www.phpbb.com/