The probabilities that a student will receive an A, B, C or D grade are 0.4, 0.3 , 0.2 and 0.1 respectively. Find the probability that a student will receive Atleast B grade.

The probabilities that a student will receive an A, B, C or D grade are 0.4, 0.3 , 0.2 and 0.1 respectively. Find the probability that a student will receive Atleast B grade.

A 0.21

B 0.3

C 0.7

D None of these

Solution

Correct Answer: Option C

P(atleast B) = P( B or A) = P(B) + P(A) = (0.3) + (0.4) = 0.7