This is the question

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%)

Typically a point in a three dimensional cartesian coordinate system is represented by which of the following answers in the picture !

Which represents the number of times all outcomes less than a given outcome occur? cumulative frequency relative frequency frequency cumulative relative frequency