Probability Crash Course

Probability Crash Course

Ways we can talk about probability..

• Probability can be stated as a fraction, decimal, or percent.

• It also can be described in words.

Certain

This occurs when all the possible choices are selected. It is certain you will spin blue since that is the conly color on the spinner.

Multiple Choice

Which example shows a certain outcome?

• You will roll a six on a die

• A coin will land on either heads or tails when tossed

Likely

This occurs when you have more than a ½ chance of an event occurring. It is likely that you will spin a blue since over half of the spinner is blue.

Multiple Choice

Which picture shows a likely chance of getting green.

Unlikely

This occurs when you have less than a ½ chance of an event occurring. It is unlikely you will spin a yellow since such a small section of the spinner is yellow.

Multiple Choice

Which picture shows an unlikely probability of getting blue?

Impossible

This occurs when the outcome doesn’t exist. It would be impossible to spin a green on this spinner.

Multiple Choice

Which example shows a result that is impossible?

• The sun will rise tomorrow

• It will snow today

• You will have two birthdays this year

• You will roll a 4 on a die

Multiple Choice

What is the probability when something is impossible?

• 0

• 1/4

• 1/2

• 1

Probability Can ONLY be between 0 and 1.

You cannot have a probability that is negative or more than 100%.

Multiple Choice

You give the answer to a probability problem as 6/5. The teacher marks it wrong. Why?

• It should have been 5/6.

• Its not written as a percent.

• Its more than 1.

• Its not written as a decimal.

How to write Probabilities...

P(event)=event we are looking for/all other possibilities

Multiple Choice

A box contains 3 black pens, 7 blue pens, and 5 red pens. Without looking, P(red or black)

• 8/15
• 15/225
• 5/15
• 3/15

Multiple Choice

What is the probability of getting any letter that is not A?

• 6/8
• 3/4
• 2/8
• 1/4

Multiple Choice

The following M & M colors are in the bowl:
4 yellow, 6 orange, 3 green, 5 blue, 2 brown.
What is the probability of selecting a brown candy?

• 2/18
• 1/9
• 2/20
• 1/10

Multiple Choice

What is the probability of rolling an even number on a dice. The dice is numbered 1-6.

• 3/6
• 1/2
• 1/6
• 5/6

Two Types of Probability:

• Experimental Probability- what actually happens when we do the experiment.

• Theoretical Probability- what SHOULD happen

Multiple Choice

The arrow is spun 15 times and landed 4 times on the section labeled Q. Which statement is true?

Multiple Choice

What is the theoretical probability for rolling a number greater than 4?

• 1/6

• 1/3

• 1/2

• 2/3

Multiple Choice

Find the experimental probability:
Roll dice:  1, 3, 3, 4, 4
P(3) = 

• 3/5
• 1/6
• 2/5
• 1/3

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

Find the theoretical probability of NOT landing on yellow if you spin the spinner.

• 1/8
• 7/8
• 1
• 7

Multiple Choice

Isidro flips a fair coin 40 times. How many times can he expect heads to appear?

• 4
• 10
• 15
• 20

Multiple Choice

What type of probability is a way of estimating the probability of an event happening based on repeated trials?

• Experimental Probabillity

• Theoretical Probability

Multiple Choice

What type of probability is a way of estimating the probability of an event happening based on repeated trials?

• Experimental Probabillity

• Theoretical Probability

Compound Probability

FInd the probability of the first event multiplied by the probability of the second event. Simplify.

Multiple Choice

What is the probability of picking a green marble, keeping it, then picking green again?

• $0$

• $\frac{1}{7}$

• $\frac{1}{49}$

• $1$

Multiple Choice

What is the probability of picking a blue marble, putting it back in the bag, then picking a red marble?

•  $\frac{3}{7}\times\frac{3}{7}$  

•  $\frac{4}{7}\times\frac{4}{7}$  

•  $\frac{4}{7}\times\frac{3}{6}$  

•  $\frac{4}{7}\times\frac{3}{7}$  

Multiple Choice

A piggy bank contains 4 quarters, 18 dimes, 10 nickels, and 8 pennies. A coin is chosen at random, not replaced, then another is chosen. Find each probability.

P (penny, then dime).

• 1/8

• 9/100

• 6/65

• 17/195

Multiple Choice

A piggy bank contains 4 quarters, 18 dimes, 10 nickels, and 8 pennies. A coin is chosen at random, not replaced, then another is chosen. Find each probability.

P quarter, then nickel).

• 1/39

• 1/20

• 10/39

• 9/195

Multiple Choice

A chorus has 50 girls and 35 boys. If two are chosen at random to sing a duet, what is the probability that both will be boys? HINT: You can not have the same person twice in a duet 

• 1/6
• 7/17
• 3/8
• 13/25

Multiple Choice

You roll a six sided die. What is the probability of rolling an even number three times in a row? 

• 3/100
• 1/2
• 1/6
• 1/8

Multiple Choice

When using a 6-sided number cube, what is the probability or rolling a 3, then not rolling a 3, and then rolling an even number?

• 1/12
• 1/2
• 5/6
• 5/72

Multiple Choice

Ricardo has the spinner pictured here and a bag of marbles filled with 2 red marbles, 3 green marbles, and 3 blue marbles. What is the probability that Ricardo spins red on the spinner and picks a red marble out of the bag?

• 1 ⁄ 16
• 1 ⁄ 2
• 1 ⁄ 4
• 1 ⁄ 8

Multiple Choice

A number cube is rolled twice. What is the probability of getting a 6 on the first roll, then a number less than 5 on the second roll? 

• 2/3
• 5/36
• 1/9
• 1/36