2.  The probability of an event is how likely it is
to occur.
 Is a number between 0 and 1.
 Probability of 1: event is certain to occur.
 Probability of 0: event will never occur.
 Probability of ½: equally likely to occur or not.

3.  When all outcomes are equally likely, the
theoretical probability that an event A will
occur is:
 Can be expressed as a fraction, decimal, or %.

4.  You roll a six-sided die with sides numbered
1 through 6. Find the probability of:
 rolling a 4.
 rolling an odd #.
 rolling a # less than 7.

5.  A spinner has 8 equal-size sections
numbered 1 though 8. Find the probability
of:
 spinning a 6.
 spinning a # greater than 5.

6.  You put a CD that has 8 songs in your CD
player and set it to random. The player plays
all 8 songs without repeating any song.
 What is the probability all songs are played in
the same order listed on the CD?
 What is the probability that 2 of your 4
favorite songs are played first, in any order?

7.  There are 9 students on the math team. You
draw their names one at a time to determine
their order at the competition.
 What is the probability that 3 of the 5 seniors
on the team will be chosen last?

8.  Five cards are drawn from a 52-card deck.
What is the probability that the first two cards
are red?

9.  It is not always possible to find theoretical
probability.
 Can sometimes find the experimental
probability using an experiment, survey, or
history of the event.

10.  In 1998, a survey asked internet users for
their ages. Find the exp. probability that a
randomly selected internet user is:
 at most 20 years old?
 at least 41 years old?
Age # of users
Under 21 1636
21 -40 6617
41 – 60 3693
61 – 80 491
Over 80 6

11.  Found by calculating the ratio of two lengths,
areas, or volumes.
 Example:
 Find the probability that a randomly thrown
dart would hit the shaded region.
4

12.  You have a 2 hour movie recorded at the
beginning of a tape that holds 6 hours of
recordings. Your brother randomly records a
30 minute show on the tape. What is the
probability that his show records over part of
your movie?

13.  A store is open from 8 am to 8 pm. The
manager works 9-4. What is the probability
that the manager is there during a random
customer’s 15 minute visit?

14.  The target for a bean-bag toss game is a
rectangle 3 ft wide and 4 ft tall with 3 circular
holes, each with radius 1 foot. What is the
probability that a random bean-bag will pass
through one of the holes?