8. A grad assistant recorded the grades for a random sample of 120 students who completed his professor's business btatistics course and also noted if the student had completed business calculus before the semester began. Below are the data: GRADE Bus Cale A B C D.F.W TOTAL Yes 23 28 13 No 19 17 9 52 TOTAL 30 47 30 15 120 (a) Construct a relative frequency bar chart for grades. (b) What percent of A students finished business calculus prior to the semester? (c) What percent of students who finished business calculus received an A in business statistics? (d) What percent of students completed business calculus and earned an A in business statistics