Standard Deviations, Z-scores

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16.  Below are the GPAs (in standard deviation units or z-scores) for three students in last year’s class of master’s students.  The average GPA was 3.5 and the standard deviation of the GPAs for the class is .5.  For each of the three students, transform the GPA into a Z-score, then indicate the approximate class rank of the student (i.e., percent of students scoring below the student).

 

 

 

 

 

                                                                                   

 

 

Student 1

Student 2

Student 3

GPA

4.0

3.7

3.0

GPA in z-score units

 

 

 

Class rank (percent of students scoring below)

 

 

 

 

 

 

17.  Use the following numbers to calculate the range, the mean, the median, the mode, and the standard deviation.  Do the calculations by hand, showing your work.  Replicate the calculations using Excel to check your work – you do not need to turn in the Excel spreadsheet.

 

 

 

                                   Data =    5, 7, 10, 12, 14, 18, 19, 19, 20, 21, 25

 

 

 

Range

 

Mean

 

Mode

 

Median

 

Standard Deviation

 

 

 

 

18.  John took two nationally normed, standardized tests and scored 700 on both tests.  The following are the results of the test for the national norming sample of students:

 

                 

 

                                                Mean               Standard Deviation

            Test 1                          1000                            300     

            Test 2                          800                              200

 

 

 

       John’s Results

 

       Test 1                   700     

 

       Test 2                   700

 

 

 

John needs to submit results of only one of the two tests to Penn in support of his college application.  Which would you advise him to submit and why? 

 

     

19.  Students in your school have been labeled “gifted” on the basis of their scores on standardized tests.  Knowing this, would you expect the correlation between achievement test scores and school grades to be higher among the gifted 12 year-olds in your school or among the entire population of 12 year olds in the school?  Why?

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