Section 2.3 Homework

1.   The accompanying frequency polygon represents the number of a​ country’s residents below 100 years of age. Complete parts​ (a) through​ (f) below.

​(a) What is the class​ width? How many classes are represented in the​ graph?

The class width is _____.  There are _____classes represented in the graph.

​(b) What is the midpoint of the first ​class? What are the lower and upper limits of the first ​class? Assume the lower and upper class limits are whole numbers.

The midpoint of the first class is

The lower limit of the first class is

The upper limit of the first class is

​(c) What is the midpoint of the last ​class? What are the lower and upper limits of the last ​class? Assume the lower and upper class limits are whole numbers.

The midpoint of the last class is

The lower limit of the last class is

The upper limit of the last class is

​(d) Which age group has the highest​ population?

10–-19

40–-49

30–-39

90–-99

​(e) Which age group has the lowest​ population?

1. 0–-9
2. 90–-99
3. 80–-89
4. 30–-39

​

(f) Which age group has 24 ​million?

1. 40–-49
2. 60-–69
3. 50–-59
4. 70–-79

2.  The accompanying relative frequency ogive represents the composite score on a standardized test for a high school graduating class. Complete parts​ (a) through​ (d) below.

(a) What is the class​ width?

​(b) Approximately 15​% of students had a composite score below what​ level?

​(c) What percentage of students had a composite score less than 36​?

​(d) Ten percent of students had a composite score above what​ level?

3.  The​ time-series plot to the right shows the annual unemployment rate and the annual inflation rate over a period of 19 years. Complete parts​ (a) through​ (f) below.

​(a) Estimate the unemployment rate in year 5. The unemployment rate in year 5 was approximately

 ​(b) In what year was the unemployment rate​ highest? The unemployment rate was highest in year

 ​(c) In what year was the inflation rate​ highest? The inflation rate was highest in year

 ​(d) In what year were the unemployment rate and inflation rate​ closest? furthest? The unemployment rate and inflation rate were closest in year

The unemployment rate and inflation rate were furthest in year _____

 ​(e) The misery index is defined as the sum of the unemployment rate and the inflation rate. According to the misery​ index, which year was more​ “miserable,” year 17 or year​ 19? The misery index for year 17 was approximately _______ and for year 19 approximately ______ so year _____was more​ “miserable.”

 ​(f) Comment on the trend in the misery index between year 6 and year 10.

Choose the correct answer below.

1. The misery index is decreasing from year 6 to year 10.
2. The misery index is increasing from year 6 to year 10.
3. The misery index decreases and then increases from year 6 to year 10.
4. The misery index increases and then decreases from year 6 to year 10.
5. The misery index is fairly constant from year 6 to year 10.

4.   The data in the table represent the stock price for a company at the end of each month in 2015.

​(a) Construct a​ time-series plot and comment on any trends.

​(b) What was the percent change in the stock price of the company from January 2015 to December​ 2015?

​(a) Which of the following is a​ time-series plot of the​ data?

Comment on any trends. Choose the correct answer below.

1. The stock price generally remained the same throughout the year.
2. The stock price generally increased throughout the year.
3. There was no discernible trend in the stock price throughout the year.
4. The stock price generally decreased throughout the year.

​(b) The percent change in the stock price of the company from January 2015 to December 2015 was ____

5.   The cumulative relative frequency for the last class must always be 1.​ Why? Choose the correct answer below.

1. The last class must always have at least one value in it.
2. All the observations are less than the last class.
3. All the observations are less than or equal to the last class.

6.  What type of variable is required when drawing a​ time-series plot? Why do we draw​ time-series plots? A ____ is required when drawing a​ time-series plot.

Select all the reasons why​ time-series plots are used.

1. ​Time-series plots are used to identify any outliers in the data.
2. ​Time-series plots are used to examine the shape of the distribution of the data.
3. ​Time-series plots are used to identify trends in the data over time.
4. ​Time-series plots are used to present the relative frequency of the data in each interval or category.