7th Grade Probability

Theoretical

1

What is the probability of rolling two odd numbers in a row with a standard number cube?

1/4, or 0.25, or 25%

2

Jarvonya spins a spinner with 5 equal sections numbered 1-5 and she spins another spinner with 5 equal sections with the letters A-E. What is the probability she will spin a 4 and a B?

1/25 or 0.04, or 4%

3

Maria is flipping a coin and spinning a spinner. The spinner has 4 equal sections labeled A-D. What is the probability the coin will land on heads and the spinner will land on the letter "A"?

1/8 or 0.125, or 12.5%

4

There are 3 red marbles, 2 green marbles, and 1 yellow marble in a box. One marble is taken out and not replaces. A second marble is then taken out and not replaced. What is the probability both marbles that were taken out are red?

1/5, or 0.20, or 20%

5

The classic wood carousel at Carousel Park in Hampton, VA has 32 jumping horses and 16 standing horses. What is the probability of randomly selecting a jumping horse?

1/2, or 0.50, or 50%

Experimental

1

A letter tile is randomly selected from a bag, recorded, and replaced 100 times. The results are listed below. What is the experimental probability of selecting the letter "E"? A = 16 E = 11 I = 29 O = 19 U = 25

11/100 or 0.11, or 11%

2

A six-sided die is thrown 50 times. Using the list below, how does the theoretical probability of rolling a 3 compare to the experimental probability of rolling a 3? Number on Die How Many Times it Landed on that Number 1 8 2 6 3 7 4 12 5 10 6 7

The theoretical probability is higher than the experimental probability. (Theoretical = 17%, Experimental = 14%)

3

Hasaan has a spinner with 5 equal sections, each a different color. After only 10 spins, the pointer had landed on red 40% of the time. After a whopping 1,000 spins, the pointer landed on red only 22% of the time. How can Hasaan account for this change in experimental probability?

As the number of trials increase, the experimental probability reaches closer to the theoretical probability. (The Law of Large Numbers)

4

Pedro recorded the types of birds that visit his bird feeder. Based on the results below, what is the probability the next bird will be a chickadee? Woodpecker = 3 Chickadee = 5 Cardinal = 1 Sparrow = 13 Blue Jay = 3

1/5, or 0.20, or 20%

5

DOUBLE PICK!!! 

What is the probability of rolling snake eyes on a dice?

1/36

Counting Principle

1

Amiya and Keyshawn are candidates for class president of the 7th grade. Ajaye, Chishon, and Laura are candidates for vice president. How many winning combinations are possible?

6

2

What is the probability of rolling three 4's in a row on a number cube?

1/216

3

You are trying to decide what to wear to school. You know you have a green pair of pants, a red pair, and a blue pair. You also have a brown shirt, a plaid shirt, and a yellow shirt. How many different outfit combinations can you make?

9

4

Ms. French is packing for a trip. She packs a white blouse, a pink blouse, a blue blouse, and a green blouse. She also packs a black suit, a navy blue suit, and a gray suit. What is the probability that the first outfit she wears is the gray suit with a pink blouse?

1 out of 12

5

What is the number of possible outcomes for spinning one spinner with 8 equal sections and another spinner with 6 equal sections?

48 possible outcomes

Vocabulary

1

Describe the difference between events that are certain, likely, equally likely, unlikely, or never going to happen.

Certain would be 100% of the time, likely is anything greater than 50% of the time, equally likely is exactly 50% of the time, unlikely is anything less than 50% of the time, and never is anything that has a 0% chance of occuring.

3

Define "theoretical probability."

It is the probability of what should occur.

4

What is probability?

The chance or odds of an event occuring

5

Define "experimental probability."

The probability of what actually occurs.

How Likely is it?

1

How likely is it that a number cube is tossed and it lands on 8?

never going to happen

2

How likely is it that a number cube lands on 2 and a coin lands on heads?

unlikely

3

How likely is it that a coin is flipped and lands on tails?

Equally likely

4

How likely is it that a number cube is tossed and lands on any number 1-6?

Certain

5

How likely is it that a number cube is tossed and lands on 3?

Unlikely