SOLUTION: There are 67 students in a chemistry class. The instructor selects a student at random. Students in a Chemistry Class Males Females Freshmen 10 15 Sophomores 13 3 Jun

 

Hi

	m	f	Tot

Fr	10	15	25

So	13	3	16

Jr	3	5	8

Sr	2	16	18

Tot	28	39	

a) What is the probability that he chooses a sophomore or a female? 16/67)+ 39/67 - 3/67)= 52/67

b) What is the probability that he chooses someone who is male and a junior? 3/67 

c) If a female is selected at random what is the probability that she is a freshmen? 

P(A|B) = P(A and B)/P(B)

P(Fr|f)=