# Activities

• • • ##### Subject Area

• Math: Statistics: Inferential Statistics

• ##### Author 9-12

60 Minutes

• ##### Device
• TI-30X IIB
• TI-30X IIS
• TI-34 II Explorer Plus™
• ##### Other Materials
This is Activity 13 from the EXPLORATIONS Book:
Math Investigations with the TI-30X IIS: Activities for Secondary Mathematics

The following materials are required for this activity:
• Stopwatch
• 3 X 5 index cards

## How Close is Close?

#### Activity Overview

Students compute statistical measures like the mean, standard deviation, and variance of the data set. They understand how measures of variability can be interpreted.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print pages 132 - 134 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to the class.

• Start a stopwatch and stop it after 20 to 30 seconds have elapsed
• Without looking at the watch, estimate and record the elapsed time
• Compare the recorded times with the actual elapsed time
• Determine the margin of error [no negative values]
• Enter the error data in a stem and leaf plot
• Find the average error
• Determine the mean absolute deviation
• Repeat the experiment and find the new average error
• Understand that the new average error should be smaller than before due to experience in estimation
• Compute the mean of the data
• Calculate Standard Deviation and understand that it is another way of measuring the amount of variation about the mean in a data set
• Repeat the calculation with other sets of data
• #### After the Activity

Students complete the Student Activity pages.

• Review student results
• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary