Question

The probabilities that a student will obtain grades A, B, C, or D are 0.30, 0.35, 0.20, and 0.15, respectively. The probability that he will receive at least a C grade is: _______

Answer 1

The probability that a student will receive at least a C grade is determined by adding the individual probabilities of getting an A, B, or C. These add up to 0.85, meaning there's an 85% chance the student will get at least a C grade.

Step-by-step explanation:

The question asks to find the probability that a student will receive at least a C grade. To determine this, we need to add the probabilities of the student receiving a grade A, B, or C. The probabilities given are 0.30 for an A, 0.35 for a B, and 0.20 for a C. Adding these probabilities together gives us:

P(A or B or C) = P(A) + P(B) + P(C) = 0.30 + 0.35 + 0.20 = 0.85.

This result means that there is an 85% chance the student will receive a grade of C or higher. Since we are given that the probabilities sum to one for all possible outcomes, which is a fundamental rule in probability theory, we can be sure that our calculation is correct, and there are no other grades to consider beyond A, B, C, and D.