Q: A Math quiz has multiple-choice questions, each with choices. A student passes the quiz with or more correct questions. If the student randomly picks their answers, what is the probability of passing the quiz?

A: 7/27 = 1/27 + 6/27

Scenario 1: The student gets all 3 correct (1/3) x (1/3) x (1/3) = 1/27

Scenario 2: The student gets 2 correct. 1/3 x 1/3 x 2/3 but this can happen 3 different ways as the student could get the 1st one incorrect or the 2nd or the 3rd.

so (1/3)x (1/3) x (2/3) x 3 = 6/27

1/27 + 6/27 = 7/27.