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Scores on a college entrance examination are normally distributed with a mean of 500 and a standard deviation of 100. What percent of people who write this exam obtain scores between 425 and 575?
a. 27.34%
b. 45.32%
c. 54.68%
d. 77.34%

 Jan 15, 2019
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Are y'all working with z-scores?     I'll have to look up my z-score table and get back in a few mins.....

  well never mind the z-scores as this is a multiple choice....

       ONE standard deviation above 500 and below 500 would be   400 and 600 

           from a standard bell curve, this represents   68%

                question asks for 425 and 575   which would be slightly LESS than 68%

                     so answer C 54.68%

 

I will check z-scores to be sure....

OK....checked z-score tables and find  54.68% 

 Jan 15, 2019
edited by ElectricPavlov  Jan 15, 2019
edited by ElectricPavlov  Jan 15, 2019

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