Random variables, probability distribution, and expected values.

If two coins are tossed, which is not a possible value of the random variable for the number of heads?

• 0

• 1

• 2

• 3

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

Given the probability distribution table below, find the value of k.

• 0.35
• 0.15
• 0.20
• 0.30

What is P( X > 2).

• 0.02

• 0.2

• 0.01

• 0.1

What is P( X <2).

• 0.2

• 0.32

• 0.02

• 0.1

Find P( X = 4).

• 1.00

• 0.91

• 0.02

• 0.07

A marketing survey compiled data on the number of cars in households.  If X = the number of cars in a randomly selected household, and we omit the rare cases of more than 5 cars, then X has the following probability distribution: 

X           0          1          2          3           4           5  

P(X)   0.24    0.37    0.20    0.11    0.05     0.03

What is the probability that a randomly chosen household has at least two cars?

• 0.20
• 0.29
• 0.39
• 0.61

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

A stockbroker estimates that at the end of the year, there is a 40% chance a stock will be worth $50, a 35% chance it will be worth $60 and a 25% chance it will be worth $70.
What expected value does this broker assign to this stock's end-of-the-year price?

• $58.50
• $60.00
• $62.50
• $65.00

In a certain community, 30% of households have 1 child, 43% have 2 children, and 27% have 3 children. If a household is selected at random, what is the expected number of children in that household? HINT: A Probability table may be helpful.

• 2.00
• 2.13
• 1.97
• 1.27