1) What does it mean for two events to be independent?
2) Suppose you are dealt one card each from two separate decks of cards. What is the probability that both of your cards are:
a) red?
b) spades?
c) jacks?
d) face cards?
3) For each situation below, determine whether the two events are independent.
a) Flip a coin and then draw a card from a standard deck of 52 cards.
b) Draw a marble from a bag, do not replace it, and then draw a 2nd marble from the same bag.
c) Get a raise at work and purchase a new car.
d) Drive on ice and lose control of your car.
e) Have a large shoe size and have a high IQ.
f) Be a chain smoker and get lung cancer.
g) Dad is left handed and son is left handed.
4) A spinner with three equal spaces of red, blue, and green is spun one time. A single six-sided die is rolled once. What is the probability that you get blue and a number greater than 3?
5) Suppose you are dealt two cards, one after another from a standard deck of cards. What is the probability that both of your cards are:
a) spades?
b) the same suit?
c) kings?
[Figure5]
6) Three cards are drawn from a standard deck without replacement. Find the probability that:
a) all are jacks.
b) all are clubs.
c) all are red cards.
7) In a carnival game, players are given three darts and throw them at a set of balloons on a wall. Suppose there are eight balloons on the wall. Five of the eight balloons have slips of paper in them that say 'Winner' while three of the eight balloons have slips of paper that are blank. Suppose you pop a balloon with each of your three darts. If all three balloons have 'Winner' slips, you win the grand prize. If all three balloons have blank slips, you win the consolation prize. What is the probability that:
a) you win the grand prize?
b) you win the consolation prize?
8) A classroom contains 12 males and 18 females. Two different students will be randomly selected to give speeches. What is the probability that the two students who give speeches are:
a) two females?
b) two males?
c) 1 male and 1 female (in either order)? (Hint: Use your answers from a) and b) along with some subtraction.)
9) If 18% of all Americans are underweight, find the probability that two randomly selected Americans will both be underweight.
10) A survey found that 68% of book buyers are 40 years old or older. If two book buyers are selected at random, what is the probability that both are 40 years old or older?
11) The Gallup Poll reported that 82% of Americans used a seat belt the last time they got into a car. If four people are selected at random, find the probability that they all used a seat belt the last time they got into a car.
[Figure6]
12) Eighty-three percent of diners favor the practice of tipping to reward good service. If three restaurant customers are selected at random, what is the probability that all three are in favor of tipping?
13) Suppose that 25% of U.S. federal prisoners are not U.S. citizens.
a) Find the probability that a randomly selected federal prisoner is a U.S. citizen.
b) Find the probability that three randomly selected prisoners are all U.S. citizens.
14) At a local university, 70% of all incoming freshmen have computers. If three students are selected at random, what is the probability that:
a) none have computers?
b) all three have computers?
15) The U.S. Department of Justice states that 6% of all murders occur without weapons. If three murder cases are selected at random, what is the probability that all three occurred with the use of a weapon?
Review Exercises
16) Which of the following are random events?
i) You need to pick 2 people to be your partners in a group project so you select two of your friends.
ii) You make a rock skip across the surface of a lake 12 times.
iii) A baby elephant is born and it is a boy.
iv) You spin the big wheel on the TV game show "The Price is Right" and you win $1000.
17) In how many ways can two 12-graders be selected for speaking at graduation if there are 16 seniors that apply? One speaker will give a short introductory speech and one will give a longer speech that reflects upon the experiences of this particular senior class.
[Figure7]
18) A family of 4 just won the lottery and goes to an auto dealership to purchase a new vehicle for each member of the family. The parents each decide that they want a car while their kids decide they would each like a truck. In how many ways can they purchase their 4 vehicles if the dealership has 17 cars and 23 trucks available?
19) The Strikers and the Kicks soccer teams are playing a best of five playoff series. The first team to win three games is the winner. Draw a tree diagram to show the different ways the series might play out.