1. Event A occurs with probability 0.2. Event B occurs with probability 0.3. Event C occurs with probability 0.4. If A, B, and C are disjoint, then:

a.P(A or B) = 0.5.

b.P(A or C) = 0.6.

c.P(A or B or C) = 0.9.

d.All of the answer options are correct

2.A group of freshmen at a local university consider joining the equestrian team. Thirty-five percent of students choose Western riding, 45% choose dressage, and 50% choose jumping. Twenty percent choose both dressage and jumping, while 10% choose Western and dressage. No one chooses Western and jumping. There are no horses suitable for two styles, and each student is assigned to one horse. What is the probability that a student chooses dressage or jumping?

a.0.95

b.0.75

c.0.23

d.0.9

3.If X has a binomial distribution with 20 trials and a mean of 6, then the success probability p is:

a.0.3.

b.0.5.

c.0.75.

d.This cannot be determined without taking a sample.