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Learning Math Home
Data Session 3, Part D: Ordering Hats
Session 3 Part A Part B Part C Part D Homework
Data Site Map
Session 3 Materials:

Session 3, Part D:
Ordering Hats (35 minutes)

In This Part: Understanding the Question | Data Analysis Using a Stem and Leaf Plot
Using a Histogram to Analyze the Hat-Size Data | Summary

In Parts A-C of this session, you learned several ways to organize numerical data by forming groups. Grouping is especially useful for wide-ranging data or data measured on the number line. Note 5

In the following activity, you will apply several of the methods you have learned for grouping data to solve a problem about how many hats to order.

Hats are made in a variety of styles and sizes. A merchant must decide what styles to keep in stock and how many of each size to order. At our theoretical hat shop, a unisex "Standard Fit" hat is available in the following sizes:

Standard Size

Head Circ. (mm)


520 to < 530


530 to < 540


540 to < 550


550 to < 560


560 to < 570


570 to < 580


580 to < 590


590 to < 600


600 to < 610


610 to < 620

Are certain hat sizes more common than others? If not, then an equal number of each hat size can be ordered. But if certain sizes are more common, the merchant needs to order larger quantities of the more common sizes.

Problem D1

write Reflect  

Before you begin, make an initial guess about whether you expect all hat sizes to be equally common. Explain your answer. If you think some hat sizes will be more common than others, which hat size would you expect to be the most common, and why?

video thumbnail

Video Segment
In this video segment, the hat-ordering problem is introduced, and participants describe their initial expectations for a hat-size distribution. Watch this segment after completing Problem D1.
How could a hat merchant determine which hat sizes are most common?

If you're using a VCR, you can find this segment on the session video approximately 7 minutes and 46 seconds after the Annenberg Media logo.


Hat size is clearly determined by head size. Several possible measurements of the human head might be used to describe head size. Mail-order catalogs ask you to measure your head circumference and then determine your hat size from a table of circumferences they provide. To find your head circumference, measure the largest part of your head by placing the measuring tape just above your eyebrows.


Problem D2


What size Standard Fit hat would you wear?

Next > Part D (Continued): Data Analysis Using a Stem and Leaf Plot

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