# Statdisk Instructions for Chapter 5 Technology Exercise

## Finding Areas (Question 1)

1. Choose Analysis / Probability Distributions / Normal
2. Enter your z-score into the box labeled z Value.
3. Leave the cumulative area from the left box blank.
4. Click Evaluate

Statdisk returns the area to the left, the area to the right, and the 2-tailed (twice the smaller value) areas.

## Finding Z-Scores (Question 2)

1. Choose Analysis / Probability Distributions / Normal
2. Leave the z Value box blank
3. Enter the appropriate value into the cumulative area from the left box
1. If your area is to the left of the z-score, enter that value
2. If your area is to the right of the z-score, subtract the area from one and then enter that value
3. If your area is something else, you'll have to find the area to the left and enter that value
4. Click Evaluate

## ACT Test Scores (Question 3)

This question is like questions 1 and 2 except we are no longer working with a standard normal distribution.

Use the formula for standardizing a variable from chapter 2 to either convert to a raw score to a z-score or from a z-score to a raw score.

That formula is z-score = (value - mean) / stdev

## Sampling Distributions (Question 4)

You don't need Statdisk or Minitab for this question. Go to the statistical demonstrations page and choose the Sampling Distribution from section 5.5.

## Confidence Interval Simulations (Question 5)

You don't need Minitab or Statdisk for this question. Go to the statistical demonstrations page and choose the Confidence Interval Simulation from section 6.2.

## Direction of Country (Question 6)

Read the Harris Poll® #16, February 16, 2006, at http://www.harrisinteractive.com/harris_poll/index.asp?PID=640

1. Choose Analysis / Confidence Intervals / Proportion One Sample
2. Enter your confidence level as a decimal
3. Enter the sample size, n, for the survey that you found for part b.
4. Enter the number of successes, x, which represents the number of people who feel that the country is seriously off on the wrong track. This is NOT the percent of people that you found for part a, but you'll have to take that percent of the total sample size and round it to a whole number to enter here.
5. Click Evaluate