We look at our third story problem.

This is a typical problem where we – as teachers of mathematics – know what kind of answer we want, i.e. a positive valued percent.  However, sometimes when creating a question, we forget how literal computers are – so we must make sure that our variables are correctly assigned.  In the Troubleshooting section of this chapter, we will discuss what happens and what to do if we make a mistake like this.

We want to use variables from our previous questions.  So let’s think about which of these variables we need to substitute for the number $12,345.21 and for the number $10,678.32.

Let S=$12,345.21 and a=$10,678.32.  Then p is positive and is the correct answer.

Step 1: Duplicating.

Here we have a question that is both related to the previous question and to that of question 3.  We choose to duplicate question 3.

• Click on question 3 (yellow background) and then duplicate this question. 
     (Press [Ctrl]+[D] or select the Question menu, then Duplicate.)

A new question 4 will appear.

• Click on the reorder button on the Toolbar.
• Click and drag question 4 into position 6.  (For more instruction see Part F, Step 1.)
• Click on OK.

Step 2: Define a list variable.

As in the above two story problems, we define a list variable – this time for the item.

• Double-click on this question (or click on Edit) to start editing this question.
• Press [Ctrl]+[D]  (or select the Edit menu and then Algorithm Definitions).
• In the Edit Algorithm Definitions box, click on New.

Define our first variable ItemList as below.  (Of course, you can type in any 5 items in the same price range – with quotation marks around and a comma after each item.)

• Click on OK.

As in Part F, Step 2, we set up the mechanism for choosing an item from this list.

• Click on New (we are still in the Edit Algorithm Definitions box).
• Define the variable that will choose a random number:  whichItem

Continuing, we define the variable which actually chooses a item.

• Click on New in the Edit Algorithm Definitions box.
• Define the variable Item that will be one of the names from our ItemList.

Step 3: Edit the existing algorithm definitions.

Since we duplicated question 3, we need to change the format as well as the range of the variables a, b and p and we need to define the variable S.

1. The variables a and b are numbers: #,###,### and have 2 fixed decimal places.

2. We define a in the range of $5000 to $15,000 with a step of 0.01 and
p in the range of 0.1% to 35% with a step of 0.1.

3. In these problems we are using the formula: S=a+b with the same formatting as for the variables a and b.

For our answer variables, we have:

4. AnsA= p.  Here are our choices for the incorrect answers.

5. AnsB=S/a  ,           AnsC=a*100/S  ,     AnsD= p*1.05.

6. In these definitions, remember to round to 2 decimal places and to change the format  
   to 2 fixed decimal places and to be numbers: #,###,###.

• Edit the algorithm definitions for the variables a, b and p.
• Define the new variable S.
• Edit the algorithm definitions for the variables AnsA, AnsB, AnsC and AnsD.

♦ If you need help in recalling exactly how to do the above steps, see Part F, Step 3.

• Finally, click on Done to close the Edit Algorithm Definitions box.
• Type in the new question, adding a “$” before every variable that represents money.

• Click on Record.

Here is our question:

Step 4: Save the file

• Save the file by pressing [Ctrl]+[S] or click on the File menu, then on Save.