Chapter 10: Performing What-If Analyses: 10-17c Apply: Case Problem 2
Book Title: New Perspectives Microsoft Office 365 & Excel 2016 Comprehensive
Printed By: Erastus Karanja (ekaranja@nccu.edu)
© 2017 Cengage Learning, Cengage Learning
Chapter Review
10-17c Apply: Case Problem 2
Data File needed for this Case Problem: Physics.xlsx
Physics 212 Professor Ian Roche teaches Physics 212 at Welles-Ryan College in Lewiston,
Maine. Professor Roche and his teaching assistants have recently scored the semester final
exam for the 204 students in the class. He wants to use Excel to determine an appropriate
grading curve. Professor Roche wants roughly the top 15 percent of his students to receive
an A, the next 40 percent to receive a B, the next 35 percent to receive a C, and the bottom
10 percent to receive a D. The professor has already created a workbook that contains the
student scores and the start of a grading scale. He wants you to use the Scenario Manager
and Solver to determine appropriate cutoff points for each grade. Complete the following:
1
Open the Physics workbook located in the Excel10 > Case2 folder included
with your Data Files, and then save the workbook as Physics Grades in the
location specified by your instructor.
2
In the Documentation worksheet, enter your name and the date.
3
In the Grade List worksheet, summarize each student’s final exam score by
adding the following calculations:
In cell B3, count the number of numeric values in column N.
In cell B4, calculate the average score in column N.
In cell B5, display the minimum score in column N.
In cell B6, use the QUARTILE.INC function to display the score for the
1st quartile from column N.
In cell B7, use the MEDIAN function to display the median exam score
from column N.
In cell B8, use the QUARTILE.INC function to display the score for the
3rd quartile from column N.
In cell B9, display the maximum exam score in column N.
4
The range D5:E8 will contain the lower and upper range for each grade, as
follows:
In the range D5:D8, enter the values 0, 70, 80, and 90 to indicate that
the lowest value Ds, Cs, Bs, and As are 0, 70, 80, and 90 points,
respectively.
In the range E5:E7, enter formulas that return a value one point less
than the lowest value for the next grade to calculate the upper limit for
each grade. For example, the formula to enter in cell E5 is =D6–1.
In cell E8, enter 100 as the upper limit for an A.
5
In the range F5:F8, enter the letter grades D, C, B, and then A, associated
with each range of exam values.
6
In column O, calculate each student’s grade with the VLOOKUP function,
using the student’s exam score in column N as the lookup value, the range
D4:F8 as the lookup table, and the third column of that table as the return
value. Use an approximate match to perform the lookup.
7
In the range G5:G8, use the COUNTIF function to count the number of exam
grades in column O within each of the four possible class grades, using the
letter grades from F5 through F8 as the criteria.
8
In cell G9, calculate the total number of grades given, confirming that it
matches the class size value listed in cell B3.
9
In the range H5:H8, enter formulas to calculate the percentage of the students
who received each grade. In cell H9, add the total percentage of the four
grades, confirming they add up to 100 percent.
10
In cell I5, enter 10% as the goal percentage of students who should receive a
D. In the range I6:I8, enter 35%, 40%, and 15% as the goal percentages for
grades C through A, respectively. In cell I9, add the four goal percentages,
confirming that they add up to 100 percent.
11
In cell J5, enter the formula =ABS(H5–I5) to calculate the absolute value of
the difference between the observed percentage of Ds and the predicted
percentage. Copy the formula to the range J6:J8 to calculate the absolute
percentage differences for the other grades. In cell J9, add the values in the
range J5:J8. This value represents the total absolute difference between the
observed distribution of grades and the grading curve that Professor Roche
wants.
12
Use the Scenario Manager to enter the three grading curves described in
Figure 10-49, using the cells in the range D6:D9 as in the input cells.
Figure 10-49
Physics 212 grading curves
13
View each scenario in the worksheet, and note which scenario results in the
lowest value for the absolute difference in cell J9.
14
Using the scenario chosen in the last question as a starting point, set up
Solver to find the optimal grading scale by doing the following:
Minimize the value of cell J9 by changing the cells in the range D6:D8.
Add the constraint that all of the values in the range D6:D8 must be
integers.
Add constraints that cell D6 (the lowest C) must fall between 50 and 70,
cell D7 (the lowest B) must fall between 60 and 80, and cell D8 (the
lowest A) must fall between 75 and 100.
Use the Evolutionary method to arrive at a solution.
15
Run Solver to find the optimal solution that minimizes the total absolute
difference. Note that the Evolutionary method may take a minute to arrive at a
solution.
16
Save the grading scale that Solver found as a fourth scenario named Optimal
Grading Curve.
17
Create a scenario summary report of the four scenarios you created showing
the ranges D5:E8 and H5:H8 as the result cells.
18
Move the answer report to the end of the workbook, and rename the sheet as
Grading Curves.
19
Save the workbook, and then close it.
Chapter 10: Performing What-If Analyses: 10-17c Apply: Case Problem 2
Book Title: New Perspectives Microsoft Office 365 & Excel 2016 Comprehensive
Printed By: Erastus Karanja (ekaranja@nccu.edu)
© 2017 Cengage Learning, Cengage Learning
© 2020 Cengage Learning Inc. All rights reserved. No part of this work may by reproduced or used in any form or by any means graphic, electronic, or mechanical, or in any other manner - without the written permission of the copyright holder.