Week 8: Quiz
Question 1
Most colleges admit students based on their achievements in a number of different areas. The grade obtained in senior level English (A, B, C, D, or F) is an example of a ________ variable.
a. Discrete
b. Ratio scale variable
c. Categorical
Question 2
A type of vertical bar chart in which the categories are plotted in the descending rank order of the magnitude of their frequencies is called a
a. Pareto Chart
b. Stem-and-leaf display
c. Contingency Table
Question 3
Referring to the table below showing durations in minutes of long-distance phone calls, what is the width of each class?
| Time (in Minutes) | Relative Frequency |
|---|---|
| 0 but less than 5 | 0.37 |
| 5 but less than 10 | 0.22 |
| 10 but less than 15 | 0.15 |
| 15 but less than 20 | 0.10 |
| 20 but less than 25 | 0.07 |
| 25 but less than 30 | 0.07 |
| 30 or more | 0.02 |
a. 1 minute
b. 5 minutes
c. 10 minutes
Question 4
The following frequency distribution table represents the average time needed by businesses to resolve cyberattacks. What percentage of businesses took between 1 and less than 14 days to resolve cyberattacks?
| Average Time to Resolve Cyber Attacks | Frequency |
|---|---|
| Less than 1 day | 101 |
| Between 1 and less than 3 days | 115 |
| Between 3 and less than 7 days | 47 |
| Between 7 and less than 14 days | 30 |
| 14 days or more | 44 |
a. 34.12%
b. 86.94%
c. 56.97%
Question 5
Which of the ordered arrays represents the following stem-and-leaf display for gasoline purchased (in gallons, leaves in tenths)?
a. Ordered array: 9.1 9.4 9.7 10.0 10.2 10.3 10.8 11.1 11.2 11.5 11.6 11.7 12.2 12.3 12.4 12.8 12.9 13.0 13.2
b. Ordered array: 9.1 9.4 9.7 10.0 10.2 10.2 10.3 10.8 11.1 11.2 11.5 11.5 11.6 11.6 11.7 11.7 11.7 12.2 12.2 12.3 12.4 12.8 12.9 13.0 13.2
c. Ordered array: 9.1 9.4 10.0 10.2 10.2 10.3 10.8 11.1 11.2 11.5 11.5 11.6 11.6 11.7 11.7 12.2 12.3 12.4 12.8 12.9 13.2
Question 6
In a right-skewed distribution,
a. the mean is equal to the median
b. the mean is greater than the median
c. the mean is less than the median
Question 7
According to the empirical rule, if the data form a “bell-shaped” normal distribution, ________ percent of the observations will be contained within 2 standard deviations around the mean.
a. 95.44
b. 68%
c. 99.7%
Question 8
According to the Chebyshev rule, at least 75% of all observations in any data set are contained within a distance of how many standard deviations around the mean?
a. 1
b. 2
c. 3
Question 9
What does the Z score measure?
a. The difference between the value and the mean, divided by the standard deviation
b. The value that seems excessively different from most of the rest of the values
c. All the above
Question 10
If the outcome of event A is not affected by event B, then events A and B are said to be
a. mutually exclusive
b. independent
c. collectively exhaustive
Question 11
If P(A) = 0.7, P(B) = 0.6, and A and B are independent, what is P(A and B)?
a. 0.13
b. 0.1
c. 0.42
Question 12
If event A and event B cannot occur at the same time, then events A and B are said to be
a. Independent
b. Collectively exhaustive
c. Mutually exclusive
Question 13
All the events in the sample space that are not part of the specified event are called
a. Simple event
b. Joint event
c. The complement of the event
Question 14
The employees of a company were surveyed on educational background and marital status. Of 600 employees, 400 had college degrees, 100 were single, and 60 were single college graduates. The probability that an employee is single or has a college degree is
a. .533
b. .667
c. .733
Question 15
From the same data as Question 14, the probability that an employee is married and has a college degree is
a. 0.567
b. .667
c. .733
Question 16
A company has 125 personal computers. The probability that any one will require repair on a given day is 0.025. To find the probability that exactly 20 require repair, what type of distribution should be used?
a. Poisson Distribution
b. Binomial Distribution
c. None of the above
Question 17
If n = 10 and the probability of an event of interest is 0.70, what is the mean of the binomial distribution?
a. .07
b. 5.0
c. 7.0
d. 14.0
Question 18
On average, 1.8 customers per minute arrive at a checkout counter. What type of probability distribution can be used to find the probability that no customer arrives?
a. No distribution fits
b. Binomial Distribution
c. Poisson Distribution
Question 19
For X = number of retransmissions to successfully transmit a 1024K data package:
| X | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P(X) | 0.35 | 0.35 | 0.25 | 0.05 |
Referring to the table, what is the mean or expected value?
a. 0.75
b. 1.00
c. 0.25
Question 20
The probability that a smoke alarm functions properly is 0.8. Two alarms operate independently. What is the probability that both sound an alarm?
a. 0.96
b. 0.64
c. 0.04
Question 21
A survey shows 60% of college students prefer energy drinks. If 5 students are chosen, what is the probability exactly 3 prefer energy drinks?
a. .2976
b. .3456
c. .3729
d. .4235
Question 22
Number of power outages at a nuclear plant follows Poisson distribution with mean 6/year. Probability of exactly 3 outages?
a. .0685
b. .0736
c. .0892
d. .0911
Question 23
X = weight of school children sampled in a nationwide study is an example of
a. a continuous variable
b. a categorical variable
c. a discrete variable
Question 24
Which of the following correctly represents attributes of a Pareto Chart?
a. Data for each category is plotted as vertical bars in descending order
b. Frequency distribution combined with cumulative percentage line
c. All the above
Question 25
Home prices in Stanislaus County: mean $266K, standard deviation $16K. According to the empirical rule, what are the upper and lower limits for 99.7% of the houses?
a. $250K and $282K
b. $234K and $298K
c. $218K and $314K
Tutorial for Quiz 8
