Arandom sample of size 36 is taken from a population with mean µ = 17 and standard deviation σ = 6. what are the expected value and the standard deviation for the sampling distribution of the sample mean?

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%)