Intro to Probability

Intro to Probability

What is probability?

• Probability is how likely something is to occur.

• Think of probability as the chance that something can or cannot happen.

For example...

IF I toss a quarter, what is the probability that I will get heads? This is really asking what is the chance that I will land on heads?

What is the probability?

When you toss a coin, the chance that it will land on heads is 1 out of 2. This is because there is 1 side that is heads and there are two total options.

Different ways to write probability

You could say that there is a 1/2 chance or 1 out of 2 chance or 50% chance

Multiple Choice

The likelihood of an event happening is _________.

• percentage

• probability

• parallel

• predictions

Multiple Choice

An event has a 50% chance of happening. This event is ___.

• Impossible

• Unlikely

• Evenly as likely as not

• Likely

• Certain

Multiple Choice

An event has a 0% chance of happening. This event is ___.

• Impossible

• Unlikely

• Evenly as likely as not

• Likely

• Certain

Multiple Choice

An event has a 75% chance of happening. This event is ___.

• Impossible

• Unlikely

• Evenly as likely as not

• Likely

• Certain

Multiple Choice

An event has a 100% chance of happening. This event is ___.

• Impossible

• Unlikely

• Evenly as likely as not

• Likely

• Certain

Multiple Choice

Can the probability of an event be zero?

• Yes

• No

Open Ended

Give an example of an event with zero probability.

What is a sample space?

• The collection of ALL unique possible outcomes in an "experiment"

• Is used to find the probability of an event occuring.

• For example, the sample space of flipping a coin is head, tails - 2 total possible outcomes.

• One more example, the sample space of choosing a letter from the alphabet is all letters a-z which is a total of 26 possible outcomes.

​Did you look at that carefully?? This will be VERY important for the rest of the slides.

​Remember the line means divide. So you will count up how many ways something can happen and divide it by the total number of outcomes.

Example 2

Multiple Choice

A letter is chosen randomly from the word ‘TERRY’.

Find the probability of choosing the letter "E".

(Hint: How many letters are in the word TERRY? How many times is there an E?)

• 1/5

• 1/4

• 3/5

• 1

Multiple Choice

A digit is chosen randomly from the date ‘01/10/2022’.

What is the probability that it is a '0'?

• 3/8

• 3/7

• 2/7

• 1/4

Multiple Choice

A fair dice is rolled. Find the probability of it landing on a ‘5’

• 5/6

• 1/6

• 2/6

• 1

Multiple Choice

A fair dice is rolled. Find the probability of getting an odd number.

• 1/3

• 1/2

• 1/6

• 0

Multiple Choice

A box contains 6 apples, 4 oranges and 5 mangoes. If a piece of fruit is drawn at random from the box, find the probability that the fruit drawn is an apple.

• 2/5

• 1/3

• 6/15

• 2/15

Multiple Choice

A box contains 6 apples, 4 oranges and 5 mangoes. If a piece of fruit is drawn at random from the box, find the probability that the fruit drawn is a peach.

• 1/5

• 0

• 4/15

• 1

Multiple Choice

Probability can be written as ...

• a fraction

• a decimal

• a percentage

• all of the above

Probability can be expressed as a fraction, decimal and percentage!

Multiple Choice

What color are you MOST likely to land on?

• pink

• green

• yellow

• blue

Multiple Choice

Jazlyn has 4 quarters, 10 dimes, and 3 nickels in her wallet.

What is the likelihood of her choosing a penny?

• certain

• likely

• unlikely

• impossible

Multiple Choice

Same situation as the last slide: Jazlyn has 4 quarters, 10 dimes, and 3 nickels in her wallet.

What is the probability of her choosing a penny?

• 4/17

• 10/17

• 3/17

• 0/17

Multiple Choice

Let's look at Jazlyn's wallet again: Jazlyn has 4 quarters, 10 dimes, and 3 nickels in her wallet.

What is the probability of her choosing a dime?

• 4/17

• 10/17

• 3/17

• 0/17

Multiple Choice

What is the likelihood of getting yellow?

• 1 out of 12

• 1 out of 8

• 3 out of 12

• 5 out of 7

Multiple Choice

What is the probability of choosing a blue section of the rectangle?

• 1/6

• 2/6

• 6/2

• 2/3

Multiple Choice

What is the probability of flipping a coin and getting heads?

• 1/2

• 1/3

• 1/4

Multiple Choice

What color is least likely to be picked?

• Green

• Black

• Light Blue

• Red

Multiple Choice

Which color is impossible to pick?

• Blue

• Yellow

• Red

• Purple

Poll

How do you feel about probability?

• Good

• Interesting

• Difficult

• Easy

• Boring