Kelly made a 94 and an 80 on the first two science tests. What does she need to make on the third test to have at least a 90 average in the class?
[(3 * 90) - (94 + 80)] / 3 = 96
To find out what Kelly needs to make on the third test in order to have at least a 90 average in the class, we can use the concept of weighted averages.
Since Kelly has taken two tests with known scores, we can calculate her current average by summing up the scores and dividing it by the number of tests taken. So, Kelly's current average is (94 + 80) / 2 = 174 / 2 = 87.
Now, let's denote the score Kelly needs to get on the third test as "x". To calculate the new average, we need to consider the weight of each test score. In this case, since all tests carry equal weight, we can assume each test to be worth 1/3 of the overall grade.
So, the equation for the new average can be written as:
(94 + 80 + x) / 3 = 90
To solve for "x", we can multiply both sides of the equation by 3 to eliminate the denominator:
94 + 80 + x = 270
Combine like terms:
174 + x = 270
To isolate "x", subtract 174 from both sides of the equation:
x = 270 - 174
Simplifying further,
x = 96
Therefore, Kelly needs to make at least a 96 on the third test to have at least a 90 average in the class.