University:
Glendale Community College
Course:
MAT142 | College Mathematics
Academic year:

2022
Views:

329

Pages:

8
Author:

slwtshx5

II. Statistical Graphs – section 3.2 Histograms and Frequency Polygons are statistical graphs used to illustrate frequency distributions. Example: Construct a histogram for the frequency distribution below. # of Children 0 1 2 3 4 5 6 7 8 9 # of families 8 11 18 11 6 4 2 1 2 1 A histogram is just a bar graph. I will make my bars go vertically. It wouldn’t be wrong if I made my bars go horizontally. Start by creating a graph of the first quadrant of an “x” and “y” axis. Use the label of the left column for the x-axis, and the label on the top of the right column for the y-axis. Place the numbers in the left column beneath the horizontal line. Place the numbers in the right column to the left of the vertical line. You may have to increment the “y-axis” when it is convenient. I incremented this y-axis by 2 as I didn’t want to write 18 numbers down. It would have been hard to read the y-axis had I written down 18 numbers. Make a rectangle above each number on the xaxis the appropriate height. This is an example of a histogram that models the data in the frequency distribution. 20 18 Number of Families 16 14 12 10 8 6 4 2 0 0 1 2 3 4 5 6 7 8 9 Number of children (It is certainly okay if the bars touch. I can’t figure out how to make that happen.) A frequency polygon is just a “line graph”. Let’s construct a frequency polygon to model the same data. I just plotted the points from the frequency distribution and then connected each point with a line segment. Example: Construct a frequency polygon for the data we used to create our frequency histogram. Number of families Start as if you were creating a histogram. Place a point above each point on the “x-axis”. Connect each point with a line segment. 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 6 Number of Children 7 8 9 10 Homework #1-4 1) Create a frequency histogram and a frequency polygon from the data in the frequency distribution below. Frequency distribution # of Children 0 1 2 3 4 5 6 7 8 9 Total # of families 8 11 18 11 6 4 2 1 2 1 64 2) Create a frequency histogram and a frequency polygon from the data in the frequency distribution below. Frequency distribution Year Unemployment rate 1920 5.2% 1930 4.2% 1940 8.7% 1950 5.3% 1960 5.5% 1970 4.9% 1980 7.1% 1990 5.6% 2000 4.0% 2010 9.6% 3) Create a frequency histogram and a frequency polygon from the data in the frequency distribution below. Put the entire class on the horizontal axis. Income (in thousands of dollars) 16-22 23-29 30-36 37-43 44-50 Total Number of families 2 5 4 3 1 15 4) Create a frequency histogram and a frequency polygon from the data in the frequency distribution below. Frequency Distribution Class 40-49 50-59 60-69 70-79 80-89 90-99 Total Frequency 7 5 3 2 7 1 25