1. Unit 6 Lesson 1
Understanding
Probability
Essential Question:
What is the likeliness of an event
occurring based on the probability near
0, 1/2, or 1?

2. Understanding Probability
• Probability is a number from 0 to 1
that shows the likelihood that an
event will occur.
– Probability close to 0 means an event is
unlikely.
• Example: Kevin Durant walking into our
math class.
– Probability close to 1 means an event is
likely.
• Example: Our entire team being promoted
to the 8th grade.

3. Example 1
Describe each
outcome using
terms such as
impossible, cert
ain, likely, or
equally likely.
Julia has a bag
with 15 colored
marbles in it.
A. The probability
that Julia will
draw a red marble
from the bag is
1/15.
B. The probability
that she will draw
a green marble is
7/15.

4. Theoretical Probability
• Theoretical probability allows us to
predict how many times an event
would likely occur in a certain
number of trials.

5. Experimental Probability
Since we do not live in a perfect
world, your prediction may be close
to, but not exactly equal to, your
results. The actual outcomes are the
experimental probability.

6. Example 2
A CD has only 1 pop song and 12
country songs on it. What is the
probability that a song randomly
selected at random will be a pop
song? Determine if the event is
likely, unlikely, or neither.

7. Are YOU
Paying
Attention?
Suppose you roll a
number cube with
faces numbered 1 to
6. What is the
probability of the
cube landing on a
number less than 7?

8. Guided Practice
• This spinner is
divided into six
congruent
sections. What is
the experimental
probability of
spinning a 2?
1. Spin the spinner
18 times.
2. Tally each time a
number is spun.
3. Total the tally
marks.
Num
ber
Tall
ies
Times
Spun
1
2
3
4
5
6

9. Guided Practice
• Compare the your experimental
probability to the theoretical
probability of spinning a 2.
 Experimental probability: _____
 Theoretical probability: _____
• The experimental probability that I
found is _______________ the
theoretical probability.

10. So, what do you remember?
Determine whether each event is
impossible, unlikely, as likely as not (
same as equally likely), likely, or
certain.
1. Bonnie’s Spanish club meets on
Tuesday afternoons. How likely is it that
Bonnie is at the mall on Tuesday
afternoon?
2. There are 12 trucks and 12 cars in a
parking lot. How likely is it that the next
vehicle to move is a van?
Find the probability.
3. It has rained on the last 2 out of 10

11. Assignments
 Classwork
1. Textbook page 630 (1 – 5)
2. Textbook page 634 (1 – 5)
 Use one answer column for both pages.
 Homework
1. Introduction to Probability worksheet.
 REMINDER: Classwork not completed in
class should be completed as homework.
 You can come in during homeroom to borrow a
textbook to complete your classwork.
 Or, you may take a picture, WITH
PERMISSION, of the pages at the end of class.