Chapter 2 Stats. McGraw Hill

Suppose a frequency distribution has the following consecutive classes: $20 up to $30 $30 up to $40 $40 up to $50 What is the class midpoint for the first class?

$25

Which of the following are characteristics of frequency distributions?

Use classes and frequencies to organize data It provides the tally for each class. Organize raw data

To divide data with a high value of H and a low value of L into k classes, the class interval must be:

at least (H-L)/k

The value shown on the vertical axis of a cumulative frequency polygon for a particular class is found by:

counting the number of observations less than the upper limit of the class

The number of observations in each class is called the class ______.

frequency

A useful way to determine the number of classes (k) in a frequency distribution of n items n.is the "2 to the k rule". Which of the following correctly describes this rule?

k is the smallest number such that 2k >n.

Which one of the following is not a characteristic of a frequency distribution?

It summarizes qualitative data.

Which of the following is an advantage of a cumulative frequency polygon over a histogram or frequency polygon?

It can show the total number of observations less than a particular class' upper limit.

Suppose that the miles per gallon for 80 cars is summarized in a frequency distribution. Below is a part of the distribution. What would the relative frequency be for the class "20 up to 24?"

0.20

Which two of the following practices are commonly used in setting class limits for a frequency distribution?

Rounding the class size up. Placing "excess" interval width equally in the two tails of the distribution.

In the histogram shown, Chart 2-4, what class had the second highest number of vehicles sold?

1400 to 1800

Given below are the data for blood types: A B B AB O O O B AB B A B 0 O O A O A A 0 A B B 0 AB Which is the frequency for blood type AB?

3

Regarding frequency tables and frequency distributions, which one of the following is true?

Both show the number of observations in each class.

What is the final step in creating a frequency distribution?

Count the number of observations in each class.

Which of the following features is not part of a histogram?

The frequency of occurrence of a nominal variable.

What information is shown on the horizontal axis of a bar chart?

The qualitative class labels.

Which of the following operations is true regarding relative frequency distributions?

The relative frequency is found by dividing the class frequencies by the total number of observations.

A frequency polygon shows the shape of a distribution and is similar to:

a histogram

In the cumulative frequency polygon shown, Chart 2-7, about how many observations are there between a value of 100 and 150?

25 Reason: To get this amount, you must subtract the cumulative frequency for 100 from that for 150.

In the histogram shown, Chart 2-4, how many vehicles were sold for a profit less than $1400?

42

In the cumulative frequency polygon shown, Chart 2-7, about how many observations are there between a value of 200 and 250?

50 Reason: You must subtract the observations for 200 from the observations for 250.

A business statistics instructor teaches a class with 83 students. Suppose he would like to create a frequency distribution to summarize their 83 final exam scores. Using the "2 to the k rule," how many classes should used?

7

Which of the following is not a useful practice in setting individual class limits for a frequency distribution?

Excluding outliers that cause the interval to be too wide.

A frequency distribution table shows the number of observations for each class interval of data. How is this data plotted as a frequency polygon?

Frequency is plotted on the vertical axis and the class midpoint is plotted on the horizontal axis.

Regarding frequency tables and frequency distributions, which of the following are true?

Only frequency tables use qualitative data. Both use mutually exclusive classes.

Which one of the following is true regarding raw data?

Raw data are simply a listing of data before summarizing it.

Which of the following is the best definition of "class midpoint"?

Halfway between the lower or upper limits of two consecutive classes.

Which of the following can be observed from a histogram? Check all that apply.

The spread of the data. The shape of the distribution. The concentration of the data. The approximate number of observations.

Which of the following features is an advantage that the frequency polygon has over the histogram?

It can directly compare two or more frequency distributions.

Which of the following is an advantage of a frequency polygon over a histogram?

It shows class midpoints as points on a polygon.