Objectives: To apply ratios to probability.

1
Lesson 4-5

• Objectives To apply ratios to probability.

2
Real World Connection

• To analyze a manufacturing situation for quality
  control, as in Example 3, p. 213.

3
Vocabulary

• Probability how likely it is that something
  will occur P(event)
• Outcome the result of a single trial, like one
  roll of a number cube
• Event any outcome or group of outcomes
• Sample space all the possible outcomes

4
Vocabulary (continued)

• Theoretical probability
• P(event) / number of possible outcomes
• what should happen
• Experimental probability
• P(event) times an event occurs / times done
• what actually happens
• Complement of an event -- all outcomes not in the
  event ( the sum of the probability of an event
  and its complement is equal to 1)

5
Complement of an Event

• Example
• If you have four envelopes labeled
• A B C D
• The probability that you will pick envelope A is
  ¼. The probability of the events complement (not
  picking envelope A) is
• 1- ¼ ¾

6
Example 1, page 212

• Suppose you write the names of days of the week
  on identical pieces of paper. Find the
  theoretical probability of picking a piece of
  paper at random that has the name of a day that
  starts with the letter T.

7
Example 2, page 212

• On a popular television game show, a contestant
  must choose one of five envelopes. One envelope
  contains the grand prize, a car. Find the
  probability of not choosing the car.
• In Example 2, what happens to P(not choosing the
  car) as the number of envelopes increases?

8
Example 3, page 213

• After receiving complaints, a skateboard
  manufacturer inspected 1000 skateboards at
  random. The manufacturer found no defects in 992
  skateboards What is the probability that a
  skateboard selected at random had no defects?
  Write the probability as a percent.
• The manufacturer (from example 3 in the book)
  decides to inspect 2500 skateboards. There are
  2450 skateboards that have no defects. Find the
  probability that a skateboard selected at random
  has no defects.

9
Example 4, page 213

• You can use experimental probability to make a
  prediction. Predictions are not exact, so round
  your results.
• The manufacturer has 8970 skateboards in its
  warehouse. If the probability that a skateboard
  has no defect is 99.2, predict how many
  skateboards are likely to have no defect.
• A manufacturer inspects 700 light bulbs. She
  finds that the probability that a light bulb
  works is 99.6. There are 35,400 light bulbs in
  the warehouse. Predict how many light bulbs are
  likely to work.

10
M M activity
11
What Colors Come in Your Bag?

• These are the percentages that was estimated by
  the M M company
• Brown 12
• Red 12
• Brown 15
• Green 15
• Blue 23
• Orange 23

12
SUMMARY

• To find theoretical probability, divide the
  number of desired outcomes by the number of
  possible outcomes. what should happen
• To find experimental probability, divide the
  number of times an event occurs by the number of
  times the experiment is done.what actually
  happens

13
ASSIGNMENT

• 4-5, page 214, 1-22 all,
• odds 23-45 and odds 51-69