Intro to Probability

Intro to Probability

Probability

• How likely is an event to occur

If I flip a coin what is the probability it lands on heads?

• P(H) = ?

• Probability (Heads)

How we do this

• # of possibilities that meet the condition

• divided by the # of equally likely possibilities

To find the probability of heads

• # of possibilities that meet the condition. How many sides on a coin are heads?

• What is the TOTAL number of sides on a coin?

Remember

Fraction bars can also represent division

Multiple Choice

What is the probability of landing on heads?

• 1/3

• 1/2

• 2/3

• 3/4

So my probability of landing on heads is

1/2 or 1 out of 2

But there are other ways to write 1/2

Multiple Choice

How do you write 1/2 as a decimal?

• .25

• .12

• .5

• .75

Multiple Choice

How do you write 1/2 as a percent?

• 25%

• .5%

• 100%

• 50%

So the probability of landing on heads is

• 1/2

• .5

• 50%

What is the probability or rolling an even number on a fair-sided dice

• P(even) =

Multiple Choice

How many even numbers are there on a fair sided dice?

• 1

• 2

• 3

• 4

Multiple Choice

How many TOTAL sides are on a fair sided dice?

• 3

• 6

• 2

• 4

Multiple Select

So how will you write your probability as a fraction?

• 3/6

• 6/3

• 4/5

• 1/2

The probability of rolling an even number is...

• 3/6 or simplified 1/2

• .5

• or 50%

Multiple Select

What is the probability of rolling a 1 or 2 on a fair-sided dice?

• 3/6

• 1/6

• 2/6

• 1/3

Multiple Choice

What is 1/3 written as a decimal? Round two decimal places

• 0.3

• 0.33

• 1.3

• 3

Multiple Choice

What is 0.33 written as a percent?

• 33%

• 0.33%

• 30%

• 3%