# Activities

• • • ##### Subject Area

• Math: Statistics: Inferential Statistics

• ##### Author 9-12

60 Minutes

• ##### Device
• TI-83
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition

TI Connect™

• ##### Accessories

TI Connectivity Cable

• ##### Other Materials
This is Activity 7 from the EXPLORATIONS Book:
Statistics Handbook for the TI-83

## Estimating and Finding Confidence Intervals

#### Activity Overview

In this activity, students estimate statistical measures and find confidence intervals.

#### Before the Activity

• See the attached PDF file for detailed instructions for this activity
• Print pages 73 - 88 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to the class.

Estimating the Mean of a Normal Population:

• Determine the mean, confidence interval, and margin of error for a sample population with normal distribution
• Find the critical z value, if the standard deviation (S.D.) is known, otherwise find the t value
• Observe that the t value > z value

• Estimating a Population Proportion:
• Check whether the product of the success percent and the sample size is greater or equal to 10
• Decide if the normal distribution can be used to approximate a binomial

• Estimating the Standard Deviation of a Normal Population:
• Enter a random sample from a population
• Determine the variance
• Plot the Chi-Square distribution
• Check the graph for symmetry
• Find the critical values
• Calculate the confidence intervals

• Estimating the Difference in Two Population Means:
• Enter random sample data sets as lists
• Determine the T interval if the standard deviations are unknown, else determine the Z interval
• Calculate the degrees of freedom, critical t or z values, margin of error, and confidence interval
• Find the mean of differences and the S.D. of differences

• Estimating the Difference in Two Population Proportions:
• Enter the data
• Calculate the critical z value, and the margin of error
• Record the percent range in which the difference in population proportions lies

• Estimators:
• Pick values from a normal distribution with a mean of 50, S.D. of 10, and variance of 100
• Obtain an unbiased variance of these values
• Generate a sequence of 100 sample variances
• Calculate the mean
• Plot a histogram
• #### After the Activity

Review student results:

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