1. Relative frequency distributions allow us to focus on

A.the part or fraction of the total frequency that occupies each class.

B.the relative density of observations among difference classes or categories within the same distribution.

C.the shapes of two or more distributions based on different total numbers of observations.

D.all of the above

2. Range of a large set of data is 12. Variance is about

A.12

B.3

C.the square root of 12

D.none of the above

3. To convert a frequency distribution into a relative frequency distribution,

A.add the frequencies of all intervals.

B.change proportions to percents.

C.divide the frequency for each interval by the total frequency for the entire distribution.

D.move the decimal point two places to the right.

4. If you wish to graph the distribution of ethnic backgrounds for a population of alcoholics, use a

A.histogram.

B.Line chart

C.stem and leaf display.

D.bar chart.

5. The height of an adult male is known to be normally distributed with mean of 175 cm and standard deviation of 6 cm. The 20th percentile (bottom 20%) of the distribution of heights is shorter than:

A.175

B.179

C.170

D.172

E.174