Question

Assume that in a statistics class the probability of receiving a grade of A equals .30 and the probability of receiving a grade of B equals .30. The probability that a randomly selected student from this class will receive either an A or a B equals:________
a. 0.09
b. 9
c. 6
d. 3

Answer 1

Answer:

c. 0.6

Step-by-step explanation:

A student cannot receive an A or a B simultaneously, so $P(A \cap B) = 0$.

Grade of A equals .30 and the probability of receiving a grade of B equals .30.

This means that $P(A) = P(B) = 0.3$

The probability that a randomly selected student from this class will receive either an A or a B equals:

This is:

$P(A \cup B) = P(A) + P(B) - P(A \cap B) = 0.3 + 0.3 - 0 = 0.6$

So the probability is 0.6, and the correct answer is given by option c.