Denise Sakai Troxell (2000) Solving Equations with Excel Solver for Microsoft Excel 2000

Denise Sakai Troxell (2000) A Simple Problem grades, grades, grades*… You would love to have a quiz average of 80 points (or better) in the QTM1300 course by the end of the semester. Your quiz scores on the first eight quizzes are given in the table below. Quiz Score What scores do you need to earn on the 9 th and 10 th final quizzes in order to meet your goal average of 80 points? * from FCL Excel Notes by Joyce Gordon, Babson College, 1998.

Denise Sakai Troxell (2000) You are looking for x = score on 9 th quiz(0 x 100) y = score on 10 th quiz(0 y 100) so that Formulate the Problem obtain equation to be solved x + y = Quiz Average NOTE: When using Excel Solver to solve an equation make sure the right-hand side is a constant.

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver start with a blank sheet

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter labels and constants Enter labels in cells A1:A13 and B1

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter labels and constants NOTE: These labels are not essential for the use of Solver

Denise Sakai Troxell (2000) enter labels and constants Preparing the Worksheet for Solver Enter constants in cells B2:B9 Remember… Score Quiz

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula Variable values in cells B10 and B11 Left-hand side of equation in cell B13 NOTE: These cells will be colored to indicate that they are essential for Solver Remember… x + y = x y

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula Click on cell B13 Remember… x + y = 80 10

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula Type in =AVERAGE( Remember… x + y = 80 10

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula Remember… x + y = Highlight cells B2:B11

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula Type in ) and hit Enter Remember… x + y = 80 10

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula NOTE: Alternative formula for cell B13: =(B2+ B3+ B4+ B5+ B6+ B7+ B8+ B9+ B10+ B11)/10

Denise Sakai Troxell (2000) Preparing the Worksheet for Solver enter formula NOTE: The function AVERAGE entered in cell B13 returns the average of the values in cells B2:B11; blank cells are ignored

Denise Sakai Troxell (2000) Using Solver invoke Solver Click on Tools

Denise Sakai Troxell (2000) Using Solver invoke Solver Click on Solver

Denise Sakai Troxell (2000) Using Solver invoke Solver

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Click on cell B13 NOTE: The cell displayed in the Set Target Cell: box must contain the formula for the left-hand side of the equation (cell B13)

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Check the Value of: circle

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box NOTE: The value displayed in the Value of: box must be the constant on the right-hand side of the equation (80) Click on the Value of: box

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box NOTE: The value displayed in the Value of: box must be the constant on the right-hand side of the equation (80) Type in 80

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Click on the By Changing Cells: box

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Highlight cells B10:B11 NOTE: The cells displayed in the By Changing Cells: box must be the cells containing variable values (cells B10:B11)

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Click on Add NOTE: The Subject to the Constraints: box must contain the constraints on the variable values (x,y 100)

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Highlight cells B10:B11 NOTE: The Subject to the Constraints: box must contain the constraints on the variable values (x,y 100) Click on the Cell Reference: box

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box NOTE: The Subject to the Constraints: box must contain the constraints on the variable values (x,y 100) Make sure <= is displayed

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box NOTE: The Subject to the Constraints: box must contain the constraints on the variable values (x,y 100) Click on the Constraint: box and type in 100

Denise Sakai Troxell (2000) Using Solver complete the Solver Parameters dialog box Click on OK NOTE: The Subject to the Constraints: box must contain the constraints on the variable values (x,y 100)

Denise Sakai Troxell (2000) Using Solver set the Options Click on Options

Denise Sakai Troxell (2000) Using Solver set the Options Check the Assume Linear Model and the Assume Non-Negative boxes NOTE: The equation (in the Target Cell B13) is linear on the non-negative variables (x in B10 and y in B11)

Denise Sakai Troxell (2000) Using Solver set the Options Accept the remaining default options by clicking on OK NOTE: The equation (in the Target Cell B13) is linear on the non-negative variables (x in B10 and y in B11)

Denise Sakai Troxell (2000) Using Solver execute Solver Click on Solve

Denise Sakai Troxell (2000) Using Solver read solution You need to earn a score of 100 on the 9 th quiz and 70 on the 10 th quiz to meet your goal average of 80 points.

Denise Sakai Troxell (2000) Using Solver end execution Click on OK

Denise Sakai Troxell (2000) Using Solver a final comment NOTE: Excel Solver might not find all possible solutions You need algebra! COMPLETE SOLUTION You need to earn a score of x on the 9 th quiz, where 70 x 100, and 170 – x on the 10 th quiz to meet your goal average of 80 points. COMPLETE SOLUTION You need to earn a score of x on the 9 th quiz, where 70 x 100, and 170 – x on the 10 th quiz to meet your goal average of 80 points.