Question

76, 85, 82, 75, 74 Kia's math test scores are shown. In order to join the math club she must have at least an 80 test score. What is the minimum score that she must make on her next test to have an average of 80? A) 83 B) 88 C) 90 D) 92

Answer 1

Her current average is 78.4, so to make an average of 80 she would have to get a score of 83 on her next test, meaning the answer is A.

Answer 2

First, we know that in order to find the average of a group of numbers, we need to add all the values together and divide by the number of values. In this case, we can write a formula for the average in order to solve for the unknown test score that Kia needs to receive: 80=(76+85+82+75+74+x)/6 (x represents the unknown test score). The reason we divide by 6 rather than by 5 is because with the new test score, there will be a total of 6 test scores. First, we can simplify the equation to 80=(392+x)/6. Then, we can cross multiply to get 80*6=392+x or 480=392+x. Lastly, we must subtract 392 from both sides to get x=88 so the answer is choice B.