A student must have an average (the mean) on five tests that is greater than or equal to 80% but less than 90% to receive a final grade of

b. devon's grades on the first four tests were 92%, 82%, 88%, and 92%. what range of grades on the fifth test would give him a b in the course?

46 < = grade < 96 First, let's write the equation for the lower limit that the student must get for a B. (x + 92 + 82 + 88 + 92) / 5 = 80 Multiply both sides by 5 giving x + 92 + 82 + 88 + 92 = 400 Subtract 92, 82, 88, 92 from both sides x = 400 - 92 - 82 - 88 - 92 = 46 So the student has to get 46 or higher on the test to make a B. Now let's compute the upper limit (x + 92 + 82 + 88 + 92) / 5 < 90 Multiply both sides by 5 (x + 92 + 82 + 88 + 92) < 450 Subtract 92, 82, 88, 92 from both sides x < 450 - 92 - 82 - 88 - 92) = 96 So the student has to get a grade of less than 96 to get a B.