1. Why is a random variable said to be "random"?
2. Indicate whether each of the following random variables is discrete or continuous.
a. The diameter of aluminum rods coming off a production line
b. The number of years of schooling employees have completed
c. The Dow Jones Industrial Average
d. The volume of milk purchased during a supermarket visit
3. Indicate whether each of the following random variables is discrete or continuous.
a. The number of drive-through customers at your local McDonald's today
b. The amount spent by all customers at the local McDonald's today
c. The time, as reported by your digital watch
d. The length of a pedestrian's stride
4. The values of x in a discrete probability distribution must be both exhaustive and mutually exclusive. What is meant by these two terms?
5. A discrete random variable can have the values x 5 3, x 5 8, or x 5 10, and the respective probabilities are 0.2, 0.7, and 0.1. Determine the mean, variance, and standard deviation of x.
6. Determine the mean, variance, and standard devia- tion of the following discrete probability distribution:
x 0 1 2
P(x) 0.60 0.30 0.10
7. Determine the mean, variance, and standard deviation of the following discrete probability distribution:
|
x
|
0
|
1
|
2
|
3
|
4
|
|
P(x)
|
0.10
|
0.30
|
0.30
|
0.20
|
0.10
|