08 Oct The numbers of hours worked (per week) by 400 statistics students are shown below. The class width for this distribution:

The numbers of hours worked (per week) by 400 statistics students are shown below.  The class width for this distribution:

 

Number of Hours             Frequency

 

0 – 9                                           20

 

10 – 19                                      80

 

20 – 29                                   200

 

30 – 39                                   100

 

Question 1 options:

 

is 9

 

is 10

 

is 39, which is: the largest value minus the smallest value or 39 – 0 = 39

 

varies from class to class

 

Question 2 A portion (subset) of a population is called a:

 

Question 2 options:

 

Statistic

 

Parameter

 

Variable

 

Sample

 

Question 3 Which ONE of the following is a discrete variable?

 

Question 3 options:

 

The number of packages delivered in one day by a delivery service

 

A person’s weight, measured in pounds

 

The time it takes a car to accelerate from 0 to 60 m.p.h., measured in seconds

 

Distance, measured in feet

 

Question 4 The owner of a factory regularly requests a graphical summary of all employees’ salaries. The graphical summary of salaries is an example of:

 

Question 4 options:

 

A sample

 

Descriptive statistics

 

Statistical inference

 

An experiment

 

Question 5 The areas under any probability distribution also represent probabilities.

 

Question 5 options:

 

True

 

False

 

Question 6 Given a normally distributed variable (x), if you know that for a value of x = 244 the z-score = 2.20, what is the probability of any x value being above 244?

 

Question 6 options:

 

0.9861

 

0.0139

 

0.0217

 

0.9783

 

Question 7 The variance of a sample of 169 observations equals 100. The standard deviation of the sample equals:

 

Question 7 options:

 

10,000

 

10

 

100

 

28,461

 

Question 8 Which measure of central tendency is at the highest point on a graph?

 

Question 8 options:

 

Mode

 

Range

 

 Median

 

Mean

 

Question 9 Which of the following symbols represents the variance of the population?

 

Question 9 options:

 

σ2

 

Σ

 

Μ

 

s2

 

Question 10 Variance is equal to the square root of the standard deviation.

 

Question 10 options:

 

True

 

False

 

Question 11 The variable “miles per hour” is an example of what level of data:

 

Question 11 options:

 

Ratio

 

 Nominal

 

Ordinal

 

Interval

 

Question 12 In calculating a binomial probability, which of the following is true?

 

Question 12 options:

 

p = the probability of success on each trial

 

x = the number of successes

 

n = the total number of trials in the experiment

 

All of the above

 

Question 13 Which of the following symbols represents the size of the sample?

 

Question 13 options:

 

Σ

 

N

 

X

 

N

 

Question 14 When calculating a binomial probability, the answer must be in the range of 0.00 to 1.00.

 

Question 14 options:

 

True

 

False

 

Question 15 The measure of central tendency that is the point at which half the scores fall above and half the scores fall below is the:

 

Question 15 options:

 

Mode

 

Range

 

Median

 

Mean

 

Question 16 Given a normally distributed variable (x), if you know that for a value of x = 3 the z-score = -1.02, what is the probability of any x value being below 3?

 

Question 16 options:

 

0.8461

 

0.1151

 

 

 

– 0.1539

 

0.1539

 

Question 17 In constructing a frequency distribution, as the number of classes are decreased, the class width:

 

Question 17 options:

 

Decreases

 

Remains unchanged

 

Increases

 

Can increase or decrease depending on the data values

 

Question 18 The difference between a histogram and a bar chart is that:

 

Question 18 options:

 

On a histogram, the y-variable is frequency

 

The x-variable has a different level of measurement

 

 On a bar chart, the columns are adjacent

 

None of the above

 

Question 19 This term refers to how data spreads out or disperses within a distribution.

 

Question 19 options:

 

Variability

 

 Critical region

 

Range

 

Mode

 

Question 20 Which of the following is not a characteristic of the normal probability distribution?

 

Question 20 options:

 

The mean, median, and the mode are equal

 

The mean of the distribution can be negative, zero, or positive

 

The distribution is symmetrical

 

The standard deviation must be 1

 

Question 21 The Nobb Door Company manufactures doors for recreational vehicles.  It has two conflicting objectives:  It wants to build doors as small as possible to save on material costs, but to preserve its good reputation with the public, it feels obligated to manufacture doors that are tall enough for 95% of the adult population in the U.S. to pass through without stooping.  In order to determine the height at which to manufacture doors, Nobb is willing to assume that the height of adults in America is normally distributed with a mean (µ) of 73 inches and standard deviation (σ) of 6 inches.  How tall should Nobb’s doors be?

 

 

 

 

 

Question 22 Here are the high temperature readings during June 2011 in Phoenix, AZ (treat these data as a sample):   84, 86, 78, 69, 94, 95, 94, 98, 89, 87, 88, 89, 92, 99, 102, 94, 92, 96, 89, 88, 87, 88, 84, 82, 87, 94, 97, 99, 102, 105.   Find the mean, median, mode, range and standard deviation. 

 

Question 23 A recent study of how Americans spend their leisure time surveyed workers employed more than 5 years.  They determined the probability an employee has 2 weeks of vacation time to be 0.45, 1 week of vacation time to be 0.10, and 3 or more weeks to be 0.20.  Suppose 10 workers are selected at random.  What is the probability that 8 workers have 2 weeks of vacation time?