Calculating Probability

In a class 20 of students, 13 have a brother and 5 have a sister. There are 2 students who have a brother and a sister. What is the probability that a student chosen randomly from the class does not have a brother? Write your answer as a fraction.

In a class 20 of students, 13 have a brother and 5 have a sister. There are 2 students who have a brother and a sister. What is the probability that a student chosen randomly from the class has a brother OR has a sister? Write your answer as a fraction.

In a class 22 of students, 15 are upperclassmen and 9 have an A in the class. There are 7 students who are upperclassman and do not have an A in the class. What is the probability that a student is an upperclassman and they have an A? Write your answer as a fraction.

In a class 22 of students, 15 are upperclassmen and 9 have an A in the class. There are 7 students who are upperclassman and do not have an A in the class. What is the probability that a student is an upperclassman OR they have an A? Write your answer as a fraction.

A box contains 2 green balls and 2 yellow balls. What is the probability of you reaching into the box and grabbing a yellow ball?

• 2/4 = 1/2

• 1/4

• 2/2 = 1

• 0

Calculate the probability of the spinner landing on a "B."

• 0/6

• 1/6

• 2/6 = 1/3

• 3/6 = 1/2

Calculate the probability of the spinner landing on a letter that is a vowel.

• 1/6

• 2/6 = 1/3

• 2/8 = 1/4

• 8/8 = 1

There is a 30% chance of rain tomorrow. How would you describe it's probability?

• impossible

• less likely

• as equally likely as not

• more likely

What is the probability of an event that is just as likely to occur as not occur? (check all that apply)

• 50%

• 3/4

• 1/2

• 6/12 = 1/2

• 0.50

How would you describe the probability of rolling a 5 on a standard 6-sided number cube?

• 0/6

• 1/6

• 2/6

• 5/6