Suppose the probability that the instructor asks Sam, one of your classmates, is 0.05 and the probability that she/he asks John, another student in your class, is 0.07. What is the probability that the instructor asks one of these two students

The probability that the instructor asks one of Sam and John whose probabilities of being asked are as indicated in the task content is; 0.12.

What is the probability that the instructor asks one of these two students?

It follows from the task content that the probability that Sam is being asked is; 0.05 while that for John being asked is; 0.07.

Consequently, we may conclude that the probability of either of the two classmates being asked the question in discuss is; the sum of the probabilities and hence, we have;

P(Sam or John) = 0.05 + 0.07

= 0.12.