each week, mandy's algebra teacher gives a 10 point math quiz. after 5 weeks, mandy has earned a total of 36 points for an average of 7.2 points per quiz. she would like to raise her average to 9 points. on how many quizzes must she score 10 points in order to reach her goal?

To solve this problem, we can set up an equation based on the given information.

Let's assume that Mandy scores a 10 on n quizzes.

We know that Mandy has taken a total of 5 quizzes and scored a total of 36 points, with an average of 7.2 points per quiz. This information allows us to set up the following equation:

(36 + 10n) / (5 + n) = 9

Here, 36 represents the total points Mandy has earned so far, 10n represents the points she will earn on the n quizzes, 5 represents the number of quizzes she has already taken, and 9 is her desired average.

To solve this equation, we can start by cross-multiplying:

36 + 10n = 9(5 + n)

Next, distribute the 9 to simplify the equation:

36 + 10n = 45 + 9n

Now, we can isolate n by subtracting 9n from both sides:

36 + n = 45

Subtract 36 from both sides:

n = 9

Therefore, Mandy needs to score a 10 on 9 additional quizzes in order to reach her goal of an average of 9 points.

guess and check is the best way!

total is 5 quizzes and she has 36 points so 7.2*5 (weeks) = 36 and add 10 to 36, 14 times so just add 140 and you get 176/19(#number of weeks 14+5) and you get 9.2 as the average. hope this is what you were looking for. sorry if its not