Introductory Statistics

Lesson 3.1 B

Objective: SSBAT find classical probability.

Standards: M11.E.3.1.1

Review:

Probability

Measures how likely it is for something to occur

A number between 0 and 1

Can be written as a fraction, decimal or percent

Probability equal to 0 Impossible to happen

Probability equal to 1 Will definitely occur

Theoretical (classical) Probability

Used when each outcome in a sample space is Equally likely to occur.

Denoted P(E) where E is the event

Also called Classical Probability

Formula:

P(E) =

Write each Probability as either a Fraction (reduced) or a Decimal.

If writing it as a decimal Round to 3 Decimal Places

Examples:

1. You roll a six-sided die. Find the Probability of rolling a 3.

There is 1 three on the die There are 6 possible outcomes in the Sample Space

P(3) =

or

P(3) ≈ 0.167

2. You roll a six-sided die. Find the Probability of rolling an even number.

Even Numbers on a die: 2, 4, 6 so there are 3 outcomes in the event

There are 6 possible outcomes in Sample Space

P(even) =

P(even) =

or

P(even) = 0.5

3. You roll a six-sided die. Find the Probability of rolling a 7.

There are no 7s on a die

There are 6 possible outcomes in Sample Space

P(7) =

P(7) = 0

4. You roll a six-sided die. Find the Probability of rolling a number less than 5.

4, 3, 2, 1 therefore there are 4 numbers < 5

There are 6 possible outcomes in Sample Space

P(# less than 5) =

P(# less than 5) =

P(# less than 5) = 0.667

5. You roll a six-sided die. Find the Probability of rolling a number greater than 0.

There are 6 numbers greater than 0 on a die

There are 6 possible outcomes in Sample Space

P(# greater than 0) =

P(# greater than 0) = 1

Standard Deck of Playing Cards52 Total Cards – 13 of each suit

Red

Red

Black

Black

6. You select a card from a standard deck. Find the Probability of selecting a Seven.

There are 4 sevens in the deck

There are 52 possible outcomes in the Sample Space

P(7) =

P(7) =

or

P(7) ≈ 0.077

7. You select a card from a standard deck. Find the Probability of selecting a Diamond.

There are 13 diamonds in the deck

There are 52 possible outcomes in the Sample Space

P(diamond) =

P(diamond) =

or

P(diamond) = 0.25

8. You select a card from a standard deck. Find the Probability of selecting a face card (K, Q, J).

There are 12 face cards in the deck

There are 52 total cards

P(face card) =

P(face card) =

or

P(face card) ≈ 0.231

9. You select a card from a standard deck. Find the Probability of selecting a Red card.

There are 26 Red cards in the deck

There are 52 total cards

P(Red) =

P(Red) =

or

P(Red) = 0.5

10. You select a card from a standard deck. Find the Probability of selecting a Diamond or a 10.

P(Diamond or 10) =

P(Diamond or 10) =

11. You select a card from a standard deck. Find the Probability of selecting a 2, 4, 6, 8, or 10.

P(2,4,6,8,10) =

P(2,4,6,8,10) = or 0.385

Insect Probability Activity

- Break students into groups- Give each group a bag of plastic insects- Give each student WS 3.1 Insect Activity

- Have students complete worksheet

On Your Own.

Use the spinner to the right to answer. Find the probability of spinning each.

a) Probability of an Odd Number

b) Probability of a number less than 6

c) Probability of a 5 or 8

Homework

Worksheet 3.1 B