Histogram

HISTOGRAMS

What are intervals again?
A _____________________is a bar graph that displays numerical data in intervals.

Example: The students of Monster High took a survey of the ages of everyone attending the “Ghouls Rule” movie. The results are in the histogram below.

Answer the following:

1) How many people from ages 10-19 attended the movie? ___________________

2) How many people aged 50 or over attended the movie? _____________________
3) How many kids younger than 20 attended the movie? _______________________
4) How many total people attended the movie? _______________________
5) What does the gap at 40-49 mean? ___________________________________________________
6) Can you tell whether a 25-year-old attended the movie? ____________ Why or why not?
_____________________________________________________________________________________

7) Why must the bars on a histogram always be touching (unless there is a gap in data)?

_____________________________________________________________________________________

MAKING A HISTOGRAM
FIRST STEP: ____________________________________________________________________________
Examples:

Data Range	Scale	Intervals
3 to 46	0 – 50	Of 10: 0-10, 11-20, 21-30, 31-40, 41-50
1 to 288	0 – 300	Of 50: 0-50, 51-100, 101-150, 151-200, 201-250, 251-300
4.1 to 5.4	4 – 5.5	Of 0.3: 4-4.2, 4.3-4.5, 4.6-4.8, 4.9-5.1, 5.2-5.4
52 to 964

SECOND STEP: _____________________________________________________

Example: Use the data in the table to make a frequency table with intervals:

Pages Read per Student Last Weekend
78	15	40	19	188
50	122	96	37	102

Since the data above ranges from 15 to 188, the scale will be ______________

and we can use intervals of _________________

Pages Read per Student Last Weekend
NUMBER:
FREQUENCY:

THIRD STEP: ________________________________________________________