# 商务统计习题

Multiple Choice: Each is worth two points

Identify the letter of the choice that best completes the statement or answers the question.

**Skip 15-17,18,20 Ch10-12,13 Material

____ 1. The sum of the relative frequencies for all classes will always equal

a. the sample size

b. the number of classes

c. one

d. any value larger than one

____ 2. The interquartile range is

a. the 50th percentile

b. another name for the variance

c. the difference between the largest and smallest values

d. the difference between the third quartile and the first quartile

____ 3. The standard deviation of a sample of 100 observations equals 64. The variance of the sample equals

a. 8

b. 10

c. 6400

d. 4,096

____ 4. The numerical value of the standard deviation can never be

a. larger than the variance

b. zero

c. negative

d. smaller than the variance

____ 5. The set of all possible sample points (experimental outcomes) is called

a. a sample

b. an event

c. the sample space

d. a population

____ 6. A random variable that can assume only a finite number of values is referred to as a(n)

a. infinite sequence

b. finite sequence

c. discrete random variable

d. discrete probability function

Exhibit 5-11

A local bottling company has determined the number of machine breakdowns per month and their respective probabilities as shown

below:

Number of

Breakdowns Probability

0 0.12

1 0.38

2 0.25

3 0.18

4 0.07

____ 7. Refer to Exhibit 5-11. The probability of at least 3 breakdowns in a month is

a. 0.5

b. 0.10

c. 0.30

d. 0.90

____ 8. A normal probability distribution

a. is a continuous probability distribution

b. is a discrete probability distribution

c. can be either continuous or discrete

d. must have a standard deviation of 1

Exhibit 6-6

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