The probability density function shown models the amount of rainfall per year for a certain location. If the area of each square on the grid is 0.05, estimate the probability that the rainfall for the year is less than 8 inches.

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%)