1. Classify the random variable X as finite, discrete infinite, or continuous, and indicate the values that X can take. According to classical mechanics, the energy of an electron in a hydrogen atom can assume any positive value. X = the energy of an electron in a hydrogen atom. X is a Finite, continuous, discrete infinite ---Select--- finite continuous discrete infinite random variable, since X can assume any positive value, any real nonnegative value, any real number, ---Select--- any positive value any real nonnegative value any real number .

2.

[-/1 Points]DETAILS

MY NOTES

Calculate the expected value of X, E(X), for the given probability distribution. E(X) =

x	10	20	30	40
P(X = x)	10 50	30 50	5 50	5 50

3.

[-/6 Points]DETAILS

MY NOTES

Your company, Sonic Video, Inc., has conducted research that shows the following probability distribution, where X is the number of video arcades in a randomly chosen city with more than 500,000 inhabitants.

x	0	1	2	3	4	5	6	7	8	9
P(X = x)	0.04	0.12	0.40	0.20	0.15	0.03	0.02	0.02	0.01	0.01

(a)

Compute = E(X). HINT [See Example 3.]

E(X) =

Interpret the result.

This is the most frequently observed number of video arcades in cities with more than 500,000 inhabitants. There are at least this many video arcades in each city with more than 500,000 inhabitants. There are at most this many video arcades in each city with more than 500,000 inhabitants. There are, on average, this many video arcades in a city with more than 500,000 inhabitants.

(b)

Find

P(X < ) or P(X > ).

P(x < )=

P(x > )=

Interpret the result.

The

P(x > )

is ---Select--- greater than or less than

P(x < ).

Thus, most cities have ---Select--- more than or less than the average number of video game arcades.

4.

[-/6 Points]DETAILS

MY NOTES

Suppose that the following figures show the price of silver per ounce, in dollars, for a 10-business-day period.

17.5, 17.2, 17.3, 17.2, 17, 16.7, 16.7, 16.7, 17.1, 16.8

Find the sample mean, median, and mode(s). (Enter multiple modes as a comma-separated list, if necessary.)

mean

median

mode(s)

What do your answers tell you about the price of silver?

Over the 10-business-day period sampled, the price of silver averaged $ per ounce. It was above $ as many times as it was below that price, and stood at $

per ounce more often than at any other price.

5.

[-/3 Points]DETAILS

MY NOTES

ASK YOUR TEACHER

The random variable X has the probability distribution table shown below.

x	2	1	0	1	2
P(X = x)	a	a	0.4	0.2	0.2

(a)

Calculate P(X 0) and P(X < 0).

P(X 0)=P(X < 0)=

(b)

Assuming

P(X = 2) = P(X = 1),

find each of the missing values.

a =