Prob and Stats Chapter 2 test

In a frequency distribution, the class width is the distance between the lower and upper limits of a class.

False. Class width is the difference between the lower (or upper limits) of consecutive classes.

What is the difference between class limits and class boundaries?

Class limits determine which numbers can belong to that class. Class boundaries are the numbers that separate classes without forming gaps between them.

Name some ways to display quantitative data graphically. Name some ways to display qualitative data graphically.

Quantitative: stem-and-leaf plot, dot plot, histogram, time series chart, scatter plot. Qualitative: pie chart, Pareto chart

What is the difference between relative frequency and cumulative frequency?

Relative frequency of a class is the portion or percentage of the data that falls in that class. Cumulative frequency of a class is the sum of the frequencies of that class and all previous classes.

Why is the standard deviation used more frequently than the variance? (Hint: Consider the units of the variance.)

The units of variance are squared. Its units are meaningless. (Example: dollars)

Explain how to find the range of a data set. What is an advantage of using the range as a measure of variation? What is a disadvantage?

The range is the difference between the maximum and minimum values of a data set. The advantage of the range is that it is easy to calculate. The disadvantage is that it uses only two entries from the data set.

The goals scored per game by a soccer team represent the first quarterly for all teams in a league. What can you conclude about the team's goals scored per game?

The soccer team scored fewer points per game than 75% of the teams in the league.

Explain the relationship between variance and standard deviation. Can either of these measures be negative? Explain.

The standard deviation is the positive square root of the variance. Because squared deviations can never be negative, the standard deviation and variance can never be negative.

The midpoint of a class is the sum of its lower and upper limits divided by two.

True

What is an advantage of using a stem-and-leaf plot instead of a histogram? What is a disadvantage?

Unlike the histogram, the stem-and-leaf plot still contains the original data values. However, some data are difficult to organize in a stem-and-leaf plot.

What must you know about a data set before you can use the Empirical Rule?

You must know that the distribution is bell-shaped.