

Subject:
statistics
Category: Miscellaneous Asked by: moneega List Price: $10.00 
Posted:
16 Feb 2005 11:07 PST
Expires: 18 Mar 2005 11:07 PST Question ID: 475565 
If a testtaker earns a zscore of +2 on a test, approximately what percentage of other testtakers obtained higher scores, assuming the distribution of test scores is normal? Would the percentage be 2%, 14%, 16% or 25%? 

Subject:
Re: statistics
Answered By: blaziusga on 16 Feb 2005 11:39 PST 
A z score of +2 implies that the testtaker scored 2 standard deviations better than the mean (see http://www.camcode.com/help/distributions/normal_distribution.htm for a more thorough description of this). You can look up the percentage on each side of any z value in an appropriate statistical table  the lower table ("Far right probabilities") at http://www.math.unb.ca/~knight/utility/NormTble.htm is helpful for solving this problem. It tells you that 0.02275 = 2,275 % of the testtakers scored better than this particular testtaker. The question asks for the approximate percentage  the best answer would be 2 %. I believe this should answer your question. If not, please request an answer clarification before you proceed to rate this answer. Search terms used on Google: "normal distribution" table "normal distribution" z 

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