The heights of the rose garden are 98 cm, 97 cm, 100 cm, 109 cm, 101 cm. what is the average height of the rose bushes in the garden

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%)