Chapter 8 Project Setting the Curve

Chapter 8 Project Setting the Curve

Name:

Date:

1

Chapter 8 Project

Setting the Curve

Dr. Groppe, a professor in the School of Computing at Klaggen University, is using a standardized final

exam that is “nationally normed” for his Computer Science II class. Nationally normed implies that the

normal distribution is an appropriate approximation for the probability distribution of students’ scores on

the exam. The probability distribution of students’ scores on this standardized exam can be estimated

using the normal distribution shown below.

In?ection

Point

In?ection

Point

x

70

78

86

1.

State the mean of the distribution of the computer science exam scores based on the figure

above.

2.

State the standard deviation of the computer science exam scores based on the figure above.

At some point in our academic pursuit, we all think that we would like our professors to curve our grades.

Especially if we’re the ones setting the curve. After considering his students’ request to curve the grades

on the final exam, Dr. Groppe has come up with two options to use if he decides to curve the grades.

Follow the steps listed to determine the grading scale for each option.

Curved Grading Option #1

• Students whose raw scores are at or above the 90thpercentile will receive an A.

• Students whose raw scores are in the 80th–89thpercentile will receive a B.

• Students whose raw scores are in the 70th–79thpercentile will receive a C.

• Students whose raw scores are in the 60th–69thpercentile will receive a D.

• Students whose raw scores are below the 60thpercentile will receive an F.

2

Chapter 8 Project

Setting the Curve

3.

In order to know the cutoff exam scores required for Curved Grading Option #1, Dr. Groppe needs to

know whatz-scorescorrespond to the upper limit percentiles. Find eachz-scorethat corresponds

to the following percentiles by using WolframAlpha online (https://www.wolframalpha.com/). For

example, inputting “z score 90thpercentile normal curve” will return thez-scoresuch that 90 percent

of data is below it in a normal curve. Round yourz-scoresto 3 decimal places. We’ve found the

z-scoreof the 90thpercentile for you.

90thpercentile

80thpercentile

70thpercentile

60thpercentile

1.282

4.

Using thez-scoresfound in Step 3, find the exam scores that correspond to Curved Grading

Option #1. Assume that the exam scores range from 0 to 100. (Round to the nearest whole number.)

Curved Grading Option #1

A:

B:

C:

D:

F:

0

–

–

–

–

–

100

Curved Grading Option #2

The second option for curving the grades is as follows:

• Students whose raw scores are at least two standard deviations above the mean of the

standardized test will receive an A.

• Students whose raw scores are from one up to two standard deviations above the mean of the

standardized test will receive a B.

• Students whose raw scores are from one standard deviation below the mean up to one standard

deviation above the mean of the standardized test will receive a C.

• Students whose raw scores are from two standard deviations below the mean up to one standard

deviation below the mean of the standardized test will receive a D.

• Students whose raw scores are more than two standard deviations below the mean of the

standardized test will receive an F.

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Chapter 8 Project Setting the Curve

3

5.

Using the information above, find the exam scores that correspond to Curved Grading Option #2.

Assume that the exam scores range from 0 to 100. (Round to the nearest whole number.)

Curved Grading Option #2

A:

B:

C:

D:

F:

0

–

–

–

–

–

100

Computer Science II

Raw Exam Scores

Name

J. Alexander

W. Thouy

C. Bradford

S. Nance

A. Moore

K. Pinkston

C. Navas

R. Alexandru

S. Garcia

Raw Score/

Uncurved Grade

79/C

69/D

88/B

66/D

75/C

86/B

91/A

77/C

82/B

A partial list of raw scores for students in

Dr. Groppe’s Computer Science II class.

6.

Using the grading scales you just created in Steps 4 and 5, complete the following table of the partial

list of grades and find the new curved letter grades that the students would receive in each of the

curving options given their raw scores on the exam.

Computer Science II Final Exam Scores

Name

J. Alexander

W. Thouy

C. Bradford

S. Nance

A. Moore

K. Pinkston

C. Navas

R. Alexandru

S. Garcia

Raw Score/

Uncurved Grade

79/C

69/D

88/B

66/D

75/C

86/B

91/A

77/C

82/B

Option #1 Curved Grade

Option #2 Curved Grade

4

Chapter 8 Project

Setting the Curve

After reviewing the grades for each student using the two optional curving methods, answer the following

questions.

7.

Who do you think benefits themostfrom Curved Grading Option #1? Why?

8.

Who is likely to disapprove of Curved Grading Option #1? Why?

9.

Who do you think benefits themostfrom Curved Grading Option #2? Why?

10.Who is likely to disapprove of Curved Grading Option #2? Why?

11.Which grading scale do you feel is mostfair? Explain why?

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