EXAMPLE 1 Making a Box-and-Whisker Plot
Roller Coasters
The heights, in feet, of 10 suspended roller coasters in the United States are 35, 42, 42.5, 60, 60, 70, 76, 78, 81, and 100. Make a box-and-whisker plot of the data.
SOLUTION
STEP 1 Find the median, the quartiles, and the extremes.
EXAMPLE 1
STEP 2Plot the five values below a number line.
STEP 3
Draw a box connecting the quartiles.
STEP 4
Draw a vertical line through the median.
STEP 5
Draw “whiskers” from the box to both extremes
Making a Box-and-Whisker Plot
EXAMPLE 2 Interpreting a Box-and-Whisker Plot
Watches
The prices of the watches at a store are summarized in the box-and-whisker plot below.
a. Suppose all of the watches under $31 are on clearance.About what fraction of the watches are on clearance?
b. Suppose all of the watches from $31 to $71 are on sale. About what fraction of the watches are on sale?
EXAMPLE 2
SOLUTION
a. The watches less than $31 are about the same as the number in one of the whiskers, which represents about one quarter of the watches.
b.The watches between $31 and $71 are about the same as the number in the large box of the plot, which represents about half of the watches.
Interpreting a Box-and-Whisker Plot
1. One weekend, a theater sold the following numbers of tickets to each screening of a new movie. Make a box-and-whisker plot of the data.
497, 429, 746, 469, 504, 464, 326, 302, 509, 467, 401, 499
GUIDED PRACTICE for Examples 1 and 2
302 415 501.5 746468
300 400 500 600 700 800
In Example 2, suppose all of the watches under $45 were on clearance. About what fraction of the watches are on clearance?
GUIDED PRACTICE
ANSWER 50%
for Examples 1 and 2
2. What If?
3. In Example 2, is the number of watches between $71 and $120 greater than the number of watches between $16 and $31? Explain.
GUIDED PRACTICE
ANSWER
No , it should be the same because the watches between $71 and $120 represent about 25% of the watches and the watches between $16 and $31 also represent about 25% of the watches.
for Examples 1 and 2