Would like some help here:

The population mean and the population variance of the final exam in CIST 2500 were 58 and 256.

a. Determine an interval for the score containing at least 40% of the students. Use Chebycheves.

b.At least what percentage of students had score between 25 and 91? Use Chebycheves.

c.Assume that the test score has a bell-shaped distribution. What should be the lowest score for a B grade

if 16% of the students are to get a grade of B or above?