(a) Cholesterol isolated from natural sources is enantiopure. The observed rotation of a 0.3-g sample of cholesterol in 15 mL of chloroform solution contained in a 10-cm polarimeter tube is 0.78. Calculate the specific rotation of cholesterol, give the complete notation of the specific rotation value assuming that Sodium-D line was used at 25 C.

(b) A sample of synthetic cholesterol consisting entirely of (+)-cholesterol was mixed with some natural ()-cholesterol. The specific rotation of the mixture was 13. What fraction of the mixture was (+)-cholesterol?