Chapter 3.2, Problem 7STP

In order to earn an A in a class, your test scores must average at least $92\%$.

On the first 6 tests, you have an average of $91\%.$

What score do you need to get on the last test to earn an A? Show your work.

To determine

To find : the score that is needed to get on the last test to earn an A.

Answer to Problem 7STP

98%

Explanation of Solution

Given information: In order to earn A in a class, the average of test scores must be atleast 92%.On the first 6 tests , average of score is 91% .

Calculation:

The average score of first 6 tests is 91%

We know that average score is ratio of sum of scores in all test to the number of test.

Therefore, sum of score in first 6 tests= 6 $\times$ 91%=546%

Let the score obtained in last test be x.

Then average of score in all 7 test = $\frac{546+x}{7}$ %

Now, to earn an A in class, the average of test scores must be atleast 92%.

Therefore, to earn an A in class

  $\begin{array}{l}\frac{546+x}{7}>92\\ 546+x>644\\ x>644-546\\ x>98\%\end{array}$

Thus, the score that is needed to get on the last test to earn an A is 98%