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On a nationwide test taken by high school students, the mean score was 54 and the standard deviation was 13. The scores were normally distributed. Complete the following statements. 

 

(a) Approximately 68% of the students scored between_____and ________.

(b) Approximately (68%, 75%, 95%, 99.7% )of the students scored between 28 and 80.

 Mar 9, 2021
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Look at your bell curve    one standard deviation above  and one standard deviation below covers approx 68 %

    54-13 = 41         54 + 13 = 67

so between   41 and 67    covers 68%

 

 

z score for 80    -    z score for 28 =

    80 is two SD             28 is - 2SD

           .9772         -      0228             =  .9544  =  ~ ~ 95%

 Mar 9, 2021

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