Unit 1 Notes ­ Day 6.notebook

1

August 29, 2013

Histograms:

• bar graphs that represent numerical data from a frequency distribution

• Contain:

> a title

> a frequency of the vertical scale

> classes on bottom or horizontal scale

Example: Ungrouped (by hand)

x f3 24 55 106 17 8

Example: Grouped (by hand)

Annual Salary (f) # of Managers15-25 1225-35 3735-45 2645-55 1955-65 6

Calculator Steps:

1. Put lower boundaries in L1

2. Put upper boundaries in L2

3. Find the midpoints in L3

> Midpoint = the number in the middle of each class

> Set a Formula: (L1 + L2)/2

4. Put frequencies in L4

Unit 1 Notes ­ Day 6.notebook

2

August 29, 2013

Graph Using Statistical Plots:

1. Press 2nd y=

2. Turn on "stat plot"

3. Set to histogram

4. Set x-list to: L3 (where x's are)

5. Set frequency to: L4 (where f's are)

6. Press Zoom Stat

7. "Fix" window with class width for x (xscl = class width)

Press "2nd y="

"fix" - make bars touch by changing the window (xscl=class width)

Unit 1 Notes ­ Day 6.notebook

3

August 29, 2013

Press "graph" when done Shapes of Histograms:

• Normal or Symmetrical

• Uniform or Rectangular

• Left Skew (negative)

• Right Skew (positive)

• Bimodal

You need to be able to recognize and name the shape of the histogram.

Example: Normal Example: Uniform or Rectangular

Example: Left Skew Example: Right Skew

Unit 1 Notes ­ Day 6.notebook

4

August 29, 2013

Example: Bimodal