# Histograms vs

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```					Bar and Histograms (What Would You Use: Part 1)

Homework
Histograms vs. Bar Graphs
Histograms and bar graphs look very similar and are used to compare data, but in different ways.
 With histograms, you have one variable, and sort data by this variable by placing them
into "bins." The main question a histogram answers is: "How many measurements are
there in each of the classes of measurements?"
 With bar graphs, you have several measurements of different items, and you compare
them. The main question a bar graph answers is: "What is the measurement for each
item?"

Below are some examples of comparisons you want to represent graphically. You need to choose
between using a bar graph or a histogram to represent the data. Which would you choose to use
in each case? Why?

Situation                Bar Graph or                   Reasoning
Histogram?
We want to compare the
total revenues of five different
companies.
We have measured revenues
of several companies. We
want to compare numbers of
companies that make from 0
to 10,000; from 10,000 to
20,000; from 20,000 to 30,000
and so on.
We want to compare heights
of ten oak trees in a city park
We have measured several
trees in a city park. We want to
compare numbers of trees that
are from 0 to 5 meters high;
from 5 to 10; from 10 to 15
and so on.

http://pulse.pharmacy.arizona.edu/math/what_would_you_use1.html
Sample Problems on Comparing Histograms and Bar Graphs

1. In the past year, you have recorded the number of tickets that a movie theater has sold during
each month. To represent this data set graphically, would you construct a bar graph or a
histogram? Why is this choice better than the other? Using the following data, construct the graph
that you choose.

Number of
Month
Tickets Sold
Jan.        25
Feb.        30
March        15
April       20
May         30
June        35
July        40
Aug.        20
Sept.       25
Oct.        15
Nov.        20
Dec.        30

http://pulse.pharmacy.arizona.edu/math/what_would_you_use1.html
2. Over the past several years, you have recorded the number of automobiles that a used car
dealer in your town has sold in different price ranges. First, decide whether a histogram or a bar
graph is most appropriate for this situation.

Next, using the given data, construct several graphs of this situation using different intervals for
the price ranges (vary the increment size--\$2,000 or \$5,000, for example). If you were the car
dealer, what increment size would you choose to advertise car sales?

Number of
Price Range
Cars Sold
\$0-\$1,000           3
\$1,000-\$1,999         5
\$2,000-\$2,999         12
\$3,000-\$3,999         25
\$4,000-\$4,999         40
\$5,000-\$5,999         75
\$6,000-\$6,999         52
\$7,000-\$7,999         35
\$8,000-\$8,999         15
\$9,000-\$10,000         9

(Source: http://www.ecu.edu/si/cd/interactivate/lessons/st5.html)

http://pulse.pharmacy.arizona.edu/math/what_would_you_use1.html

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