Which of the following is NOT a rate? A
6 meters per second
O
B. 15 dollars per hour
C. 3 seconds per second
D. 2 dollars per pound

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)