Probability: Outcomes & Events Lesson 2

Probability: Outcomes & Events Lesson 2

NC.7.SP.5 Understand that the probability of a chance event is a number between 0 and 1 that expresses the likelihood of the event occurring.

Objective: You will be able to find the probability of an event.

NC.7.SP.5 Understand that the probability of a chance event is a number between 0 and 1 that expresses the likelihood of the event occurring.

Review

An experiment is the process of investigating something where we test or look for something, make observations, and collect data...

Mathematical Experiments

to find the possibility that a particular event will occur

Experimental Probability

'the likelihood of a particular event occurring based on experimental data or observations'

Yesterday, we started looking at different experiments and we considered the favorable and possible outcomes...

We said a favorable outcome is the outcome of a specific event while the collection of one or more outcomes is an event.

For example,

For example, if we want a yellow marble...

Choosing a yellow marble is a favorable event and the favorable events would be yellow, yellow, yellow.

Multiple Choice

If choosing NOT choosing a yellow marble is a favorable outcome, how many ways could we NOT choose a yellow marble?

• 18

• 3

• 15

• 0

Experimental Probability

We know what experiments are... but what exactly do we mean when we say probability?

Probability: 'a number that describes measures the likelihood that an event will occur'

1. Experiment

2. Collect data

3. Use data to make predictions

*These predictions are the probabilities of the event happening again!

Probability

• Probabilities are always between o and 1

• A probability of 0 means that the event is impossible.

• A probability of 1 means that the event is certain.

Probability can be expressed as a fraction, decimal, or a percentage:

A  $\frac{1}{2}$  probability would be the same as a probability of 50% and a probability of 0.5.

How do we find the probability of an event?

P(event) =   $\frac{number\ of\ favorable\ outcomes}{number\ of\ possible\ outcomes}$  

Multiple Choice

What is the probability of rolling a cube and having it land as a six?

• 1/6
• 5/6
• 1/3
• 1/2

Multiple Choice

You roll a 6-sided die.

What is P(1)?

• 1/6

• 2/5

• 1/9

• 2/3

Multiple Choice

A spinner has 10 equal sections, of which 4 are orange. If you spin the spinner once, what is the probability that it will land on an orange?

• 2/5

• 1/5

• 1/10

• 5/2

Multiple Choice

Muffin Extravaganza has 34 muffins for sale, including 10 blackberry muffins.

What is the probability that a randomly selected muffin will be a blackberry muffin?

• 5/17

• 1/34

• 10/34

• 17/34

Multiple Choice

Gabby is picking out fabric for her bedroom. She has 20 fabric samples, and 8 of them are plaid.

What is the probability that a randomly selected fabric sample will be plaid?

• 12/20

• 2/5

• 1/20

• 20

Multiple Choice

You pick a card at random.

What is P(5)?

• 1/4

• 3/4

• 4/3

• 4

Multiple Choice

You spin the spinner 1 time.

What is P(7)?

• 1%

• 50%

• 20%

• 25%

Multiple Choice

Find the experimental probability:

Roll dice: 1, 3, 3, 4, 4

P(1) =

• 3/5

• 1/6

• 2/5

• 1/5

Multiple Choice

What is the probability that you choose blue? *simplify

5 green

6 yellow

8 blue

7 brown

• 8/26

• 4/13

• 8/25

• 1/3

Multiple Choice

P(not A) =

*Remember to simplify.*

• 6/8

• 3/4

• 2/8

• 1/4

Multiple Select

What is the probability of spinning a 2 on the spinner?

• 1/2

• 1/3

• 1/8

• 1/4

Multiple Choice

What is the probability the spinner stops on yellow?

• .05

• 50%

• 25%

• 3/8