7th Grade Probability

Theoretical

100

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%

200

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%

300

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

1/4, or 0.25, or 25%

400

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%

500

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%

Experimental

100

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)

200

Sydney has a bag containing 6 red, 4 blue, and 5 green marbles.  She picks a marble, records the color and puts it back then she does it again.  She does this for a total of 12 times and pulled a red marble 8 times.  What is the experimental probability of pulling a red marble?

2/3

300

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%

400

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%

500

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%)

Counting Principle

100

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

200

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

300

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

400

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

500

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

1/216

Compound Probability

100

A bag contains the following marbles: 6 red, 4 orange, 3 yellow, 2 blue, and 5 green.  You choose a marble at random and do NOT replace it.

What is the probability that you choose red, then blue?

3/10

200

You roll a dice and toss a coin.  What is the probability of rolling a multiple of 2 and flipping heads?

1/4

300

You have 20 pencils of assorted colors:  6 green, 5 blue, 7 pink, and 2 purple.  You randomly select two pencils.  What is the probability of selecting purple then pink?

7/190

400

You fix a 24 cookies, 12 chocolate chip, 7 peanut butter, and 5 sugar cookies.  You decide you are hungry and want to eat two cookies.  What is the probability that the first cookie you eat is peanut butter and the second cookie is a sugar cookie?

35/576

Independent vs Dependent

100

You toss a coin then roll a number cube

independent

200

You draw a card, do not replace it and draw another card

Dependent

300

A penny landing on heads and a dice landing on 4

independent

400

Eating a cookie, then eating a second cookie

dependent

500

What is the probability of picking a red 2 then a black 2?

1/676