12.01 Discussion: Find the Average Review the following example problem:

Greta has earned the following scores on her first three exams: Exam 1 = 82%, Exam 2 = 88%, Exam 3 = 94%.
What percentage does Greta need to earn on Exam 4 to get at least a 90% average on her four exams?

Step 1: Find the mean of the first three exam scores. Add up all of the scores.
82 plus 88 plus 94 equals 264
Step 2: Divide the total by the number of scores.
264 over 3 equals 88
The mean of the first three test scores is 88.
Step 3: Before you can find the number of points Greta needs on Exam 4, you need to know the total score Greta needs to have an average of 90% on her four exams. Multiply 4 times 90.
4 times 90 equals 360
Step 4: To find how many points Greta needs on Exam 4, assign a variable for Exam 4.
t = number of points scored on Exam 4
Step 5: There was a total of 264 points in the first three exams. You need to add in the score from Exam 4.
264 plus t equals 360
Step 6. Use a related equation that puts the variable by itself on one side of the equation.
360 − 264 equals t
Step 7. Subtract.
t equals 96

Greta will need to score a 96% on Exam 4 to average 90% on her four exams.

A. Now write your own problem. Change the scores for Exams 1 through 3 in the example problem and post your new problem to the discussion board.
B. Respond to two other students’ posts and solve their problem for what score is needed on Exam 4 to earn a 70%, 80%, or 90%. Be sure to answer whichever has not already been done.