Bert got grades of 86, 66, and 91 and 93 in 4 Math tests. What must be the 5th grade so that he gets an average of 90? (with explanation pls)
Answer:
To find the grade Bert needs to get an average of 90, we can use the formula for the average:
Average = (sum of all grades) / (number of grades)
In this case, Bert has taken four math tests, and we know his grades for three of them. Let’s call his missing grade “x”. Then we can set up an equation:
(86 + 66 + 91 + 93 + x) / 5 = 90
We want to solve for “x”. We can start by multiplying both sides by 5 to get rid of the fraction:
86 + 66 + 91 + 93 + x = 450
Next, we can combine the numbers on the left-hand side of the equation:
336 + x = 450
Subtracting 336 from both sides gives:
x = 114
So Bert needs to get a grade of 114 on his fifth math test in order to have an average of 90.
