StarterStarter

Draw a number line and work out the following:

1. What is a fraction that is between one half and one third?

2. What is a fraction that is between two fifths and one quarter?

3. What is a fraction that is between two thirds and 4 fifths?

0 1½

LI: To understand Probability and LI: To understand Probability and ChanceChance

SC: Calculate Probabilities

ProbabilityProbability

Probability is a measure of how likely it is for an event to happen.

We name a probability with a number from 0 to 1.

If an event is certain to happen, then the probability of the event is 1.

If an event is certain not to happen, then the probability of the event is 0.

ProbabilityProbability

If it is uncertain whether or not an event will happen, then its probability is some fraction between 0 and 1 (or a fraction converted to a decimal number).

1. What is the probability that the spinner will stop on part A?

2. What is the probability that the spinner will stop on

(a) An even number?(b) An odd number?

3. What fraction names the probability that the spinner will stop in the area marked A?

ABC D

3 12

AC B

Probability ActivityProbability Activity

Obtain a handful of glass pebbles.Put ten of one colour (white) and five of

another colour (black) in a container.Ask your group, what is the probability of

getting a white one?Ask your group, what is the probability of

getting a black pebble?

Another person in the group will then put in 8 white pebbles and 2 black ones in.

Ask the group to predict which color you are more likely to pull out, least likely, unlikely, or equally likely to pull out.

The last person in the group will make up his/her own problem with the glass pebbles.

Probability QuestionsProbability Questions

Lawrence is the captain of his track team. The team is deciding on a color and all eight members wrote their choice down on equal size cards. If Lawrence picks one card at random, what is the probability that he will pick blue?

yellow

red

blue blue

blue

green black

black

Donald is rolling a number cube labeled 1 to 6. Which of the following is LEAST LIKELY?

A. an even number

B. an odd number

C. a number greater than 5

CHANCECHANCE

Chance is how likely it is that something will happen. To state a chance, we use a percent.

0½

Probability1

Certain not to happen

Equally likely to happen or not to happen

Certain to happen

0% 50 %

Chance

100%

ChanceChance

When a meteorologist states that the chance of rain is 50%, the meteorologist is saying that it is equally likely to rain or not to rain. If the chance of rain rises to 80%, it is more likely to rain. If the chance drops to 20%, then it may rain, but it probably will not rain.

1. What is the chance of spinning a number greater than 1?

2. What is the chance of spinning a 4?

3. What is the chance that the spinner will stop on an odd number?

4. What is the chance of rolling an even number with one toss of on number cube?

1 24 3

4 12 3

5

Probabilities when Outcomes Probabilities when Outcomes are Equally Likelyare Equally Likely

Math MessageMath Message

Which phrase –

Extremely likely 50-50 chance, or Very Unlikely

best describes the chance of picking a red card from a regular deck of playing cards?

Words we use to describe Words we use to describe the likelihood of eventsthe likelihood of events

ImpossibleExtremely unlikely

Very unlikelyUnlikely

50-50 or even chanceLikely

Very likelyExtremely likely

Certain

Comparing Two EventsComparing Two Events

More likely

Equally likely

Less likely

Picking a heart is _____________ than picking the 9 of hearts.

Comparing Two EventsComparing Two Events

More likely

Equally likely

Less likely

Picking a red card and picking a black card are ____________.

Comparing Two EventsComparing Two Events

More likely

Equally likely

Less likely

Picking a face card is _______ than picking a non-face card.

Finding the Probability of Finding the Probability of EventsEvents

When you randomly draw a single card from a deck of cards, 52 equally likely results or OUTCOMES are possible.

An event is the specific set or collection of possible outcomes in which you are interested.

Probability is the number from 0 to 1 that tells the chance that an event is going to happen.

FormulaFormula

Probability of an event = number of favorable outcomes

number of possible outcomes

A favorable outcome is an outcome that meets the conditions of an event that will make the event happen.

Picking a heart is an event. A favorable outcome is picking a 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K, or A of hearts.

There are 13 favorable outcomes out of 52 possible outcomes.

The probability of the event is = 13 52

PracticePracticeProbability of an event = number of favorable outcomes

number of possible outcomes

Picking a face card is an event.

A favorable outcome is picking a J, Q, or K of hearts, diamonds, spades, or clubs.

How many favorable outcomes are there? ____

How many possible outcomes are there? ____

So the probability is ____

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BrainPOP | Basic Probability