SK Average Points Scored Per Minute
The first table below shows the total number of points
scored up to the number of minutes listed.
In the second table, compute the average number
points scored per minute in the periods described.

Worth 19 pOInTs PLZ help

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%)