geometry homework

Question

In a class of 30 students, 15 own an iphone, 10 own an ipad, and 2 own both. What is the probability that a student chosen at random owns either an iphone or an ipad?

a. 12/15

b. 27/30

c. 5/6

d. 23/30

Answer 1

Event A = own iPhone. P(A) = 15/30

Event B = own iPad P(B) = 10/30

P (A and B) = 2/30

P(A or B) = P(A) + P(B) - P(A and B) = 15/30 + 10/30 - 2/30 = 23/30 (d)