Basics of Probability and Counting

Which one of the following is a discrete random variable?

• Sam's height

• Sam weight

• Time Sam's runs the 110 m hurdles

• Amount of Sam's brothers and sisters

Classify: How many miles it takes to use up a tank of gas.

• Discrete

• Continuous

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

The table above shows a television station's advertisement sales. The distribution of sales for one 24-hour day is given. Solve for the expected mean. Round to the nearest hundredth.

• 31.8

• 15.68

• 0.20

• 1.00

An algebra 2 test has 6 multiple choice questions with four choices with one correct answer each. If we just randomly guess on each of the 6 questions, what is the probability that you get exactly 3 questions correct? (hint: P(A)=1/4 P(B)=3/4, P(3AU3B)=? and how many arrangement of these?)

• 96.2%

• 13.2%

• 8.31%

• 25.0

• Discrete
• Continuous

While driving to Florida, Sophia averaged 72 m.p.h. 

• Discrete
• Continuous

The table represents the probability of guessing correct on a 5 question true-false quiz.  Find the probability for at least 4 questions correct.

• .03125
• .15625
• .3125
• .1875

Is this a probability distribution?

• No
• Yes

Find the missing value for P(X=5) in the probability ditribution:

Number of Toys | Probability

0| 0.03

1| 0.16

2| 0.30

3| 0.23

4| 0.17

5| ?

• 0.11

• 0.21

• 0.01

• 0.31