8.1 Coach

Serafina tallies how often a spinner lands on different colors. She spins 50 times and gets the results pictured. What can Serafina conclude is the approximate probability of the spinner landing on yellow the next time she spins?

• 1.0

• 0.2

• 10

• 0.25

• 0.1

Answer explanation

The missing number is 10, and 10/50 = 0.2

Mary's sock drawer is filled with pairs of black, red, green, and yellow socks. Mary wants to know the probability of picking a particular color if she chooses at random. 

Suppose that she knows that the probability of picking a black pair is 0.5, the probability of picking a red pair is 1/12, and the probability of picking a green pair is 25%. What is the probability that Mary picks a yellow pair?

• 10%

• 20%

• 1/6

• 1/12

The Mathland Middle School math team is having a fundraising raffle, where you can win one of three cash prizes.

The probability of winning $2 is 0.05; the probability of winning $5 is 1/25; and the probability of winning $10 is 2%. What is the probability of not winning anything?

• 0.70

• 3/4

• 4/5

• 89%

A bag of different colored candy contains 20 red, 13 blue, 8 yellow, and 9 green pieces of candy. Without looking into the bag, one piece of candy is selected. What is the probability that the candy is blue?

• 0.09

• 0.13

• 0.26

• 0.40

Andrew has a container with 80 game pieces that are different colors. He knows that the probability of choosing a green piece at random from the container is 0.20 and the probability of choosing a yellow piece at random from the container is 0.45.

There are a total of __ yellow or green game pieces.

A middle school has sixth grade, seventh grade, and eighth grade students. There are 136 sixth graders and 119 seventh graders. The probability of selecting an eighth grader randomly from all of the students is 0.25.

There are __  eighth grade students.

Samantha records the heights of a sample group of seventh grade students. She determines that the ratio of students under 54 inches tall to students 54 inches and taller is 3:2.

What is the probability that a student selected at random is under 54 inches tall?

• 0.20

• 0.30

• 0.40

• 0.60