1/04 Math 2: Intro to Probability

Intro to Probability

What is Probability?

The extent to which an outcome is likely to occur

Sample Space

The possible outcomes that are likely to occur

Probability is written as:

 $P\left(event\right)=\frac{the\ outcome\ of\ the\ desired\ event}{the\ total\ possible\ outcomes}$  

Events

Tossing a Coin

When tossing a two-sided coin, there are only two possible outcomes: Heads or Tails.

What is the probability?

The probability of a coin landing on heads is 1 out of 2. This is because there is only 1 side that has a head out of 2 sides on the coin.

There are different ways to write probability

•  $as\ a\ fraction:\ \frac{1}{2}$   
  

• as a decimal: 0.5

• as a percentage:  50%

Probability of the Spinner

• Look at the spinner at the right.

• How many possible outcomes are there?

Multiple Choice

P(Blue) =

• 1/3

• 1/4

• 1/5

• 1/6

Multiple Choice

P(Yellow) =

• 67%

• 40%

• 50%

• 83%

Multiple Choice

P(Not Orange) =

• 0.25

• 0.1

• 0.8

• 0.9

Multiple Choice

P(Green) =

• 0/10

• 1/10

• 4/10

• 3/10

6-Sided Die

The sample space for rolling a standard die is: {1, 2, 3, 4, 5, 6}

Each outcome is equally likely

Multiple Select

P(a number greater than 4) =

select all that apply

• 1/3

• 1/2

• 2/6

• 1/6

Multiple Choice

P(a prime) =

• 1/3

• 2/3

• 1/2

• 1/6

Standard Deck of Cards

• 52 Cards

• 26 Red, 26 Black

• 12 Face Cards (Jack, Queen, and King)

• 13 cards in each suit

• 4 Suits (Clubs, Spades, Hearts, and Diamonds)

Multiple Choice

P(Red) =

• 1/2

• 1/13

• 1/52

• 1/26

Multiple Choice

P(King) =

• 1/52

• 1/26

• 1/13

• 1/2

Multiple Choice

P(Black Jack) =

• 1/52

• 1/13

• 1/2

• 1/26

Multiple Choice

P(Queen of Hearts) =

• 1/52

• 1/2

• 1/26

• 1/13

Multiple Choice

If you select a marble without looking, what is the probability that it will be blue?

• 1/3

• 2/5

• 1/6

• impossible

Multiple Choice

If you reach in the bag and pull out a marble. What is the probability that it will be green?

• 1/5

• 1/2

• 5/9

• impossible

Multiple Choice

A bag has 3 red marbles, 2 blue and 4 yellow. What is the theoretical probability of pulling a red?

• 3/10
• 3/9
• 1/9
• 1/3

Multiple Choice

A jar contains 2 pink, 6 red, and 4 blue marbles. If you pick one marble without looking, what is the probability that the marble you pick will be red or blue?

• 5/6
• 1/2
• 1/3
• 1/6

Multiple Choice

What is the probability of pulling a red marble
out of a jar of marbles that have 10 green marbles, 7 red marbles and 3 blue marbles?

• 1/7
• 7/20
• 7/10
• 3/10

Closure:

Multiple Choice

Probability is ...

• the chance that some event will occur.
• a game that involves coins.
• a guarantee.

Multiple Choice

A set of all possible outcomes is known as - 

• a list
• a complement
• a sample space
• an event

Multiple Choice

Probability can be written as ...

• a fraction
• a decimal
• a percent
• all of the above

Multiple Choice

How do you write 0.02 as a percent?

• 20%
• 200%
• 2%
• .02%

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 of drawing a black 5 from a standard deck of playing cards?

• 1/2
• 4/52
• 1/13
• 1/26