Question

Sandra's scores on the first 4 tests were 87%, 92%, 76%,and 89%. What is the minimum score she needs to make on the fifth test so the her average is at least an 80%?

Answer 1

Answer:

Sandra need to score at least 56% in her fifth test so that her average is 80%.

Step-by-step explanation:

Given:

First 4 test scores = 87%, 92%, 76%,89%

Average targeted = 80%

We need to find the minimum score she needs to make on fifth test to achieve average of at least 80%.

Solution:

Let the minimum score she needs to make in fifth test be 'x'.

Total number of test = 5

Now we know that;

Average is equal to sum of all the scores in the test divided by number of test.

framing in equation form we get;

$\frac{87+92+76+89+x}{5}=80$

Multiplying both side by 5 we get;

$\frac{344+x}{5}\times 5=80\times 5\\\\344+x=400$

Subtracting both side by 344 we get;

$344+x-344=400-344\\\\x=56\%$

Hence Sandra need to score at least 56% in her fifth test so that her average is 80%.