Histograms

Histograms

Learning Objectives

• Read and interpret histogram with equal interval

• Read and interpret histogram to find the frequency density of different classes

What is a histogram?

• A specialized graph looks like a bar chart

• Normally used to show a distribution of continuous or grouped data

Open Ended

Write examples for discrete and continuous data (3 each)!

Example 1

​Example 2

Answer

Example 3

Multiple Choice

How many trees are at least 15 feet tall?

• 12 trees

• 2 trees

• 9 trees

• 41 trees

Multiple Choice

21. How many students are represented by the histogram?

• Cannot be determined

• 9

• 31

• 35

Multiple Choice

How many students are between 48 and 51 inches tall?

• 14

• 8

• 2

• 0

Multiple Choice

What is an interval?

• A single number
• A range of numbers
• A percentage
• A total amount

Multiple Choice

Which interval has 400 employees?

• 33-43

• 0-10

• 77-87

• 66-76

Multiple Choice

Which interval has 400 employees?

• 33-43

• 0-10

• 77-87

• 66-76

Histogram with unequal class interval

​It looks as though there is more data in the 10 < t ⩽ 20 interval than in the 20 < t ⩽ 25 interval, but there were actually 20 values in both.

​compare with:

Multiple Choice

What is the frequency density in the interval 20-25?

• 4

• 3

• 2

• 0.5

Multiple Choice

What is the frequency in the interval 20-25?

• 40

• 30

• 20

• 5

Multiple Choice

What is the frequency in the interval 40-60?

• 40

• 30

• 20

• 10