Download Probability WS 3

AP Statistics
Probability Practice 3
Name: __________________________
Day 3:
1) A student placement center has requests from 5 students for interviews regarding employment. Three of
these students are math majors and two are statistics majors. Unfortunately, the interviewer has time to talk
to only two students randomly selected from the five. (POD, p. 294)
a) What is the probability that both selected students are statistics majors?
b) What is the probability that both selected students are math majors?
c) What is the probability that at least one of the selected students is a statistics major?
d) What is the probability that selected students have different majors?
2) Consider a system consisting of four components, as
1
2
pictured in the diagram. Components 1 and 2 form a series
subsystem, as do components 3 and 4. Suppose that
3
4
P(1 works) = .9, P(2 works) = .9, P(3 works) = .9, and
P(4 works) = .9 and that the four components work independently of one another. (POD, p.314)
a) The 1-2 subsystem works only if both the components work. What is the probability of this happening?
b) What is the probability that the 1-2 subsystem does NOT work?
c) What is the probability that the 3-4 subsystem does not work?
d) The system will only work if both the subsystems work. What is the probability of this happening?
3) Consider a standard deck of cards.
a) One card is selected at random. What is the probability that the card is a “king” or a “queen”?
b) One card is selected at random. What is the probability that the card is a “king” or a “black” card?
c) Two cards are selected at random with replacement. What is the probability that both cards are a diamond?
d) Two cards are selected at random without replacement. What is the probability that both cards are a
diamond?