Minitab Instructions for Chapter 5 Technology Exercise

Minitab ALWAYS returns the area to the left of a z-value.

Finding Areas (Question 1)

This uses the cumulative probability distribution, which is the area to the left of the z-score.

Choose Calc / Probability Distributions / Normal
Make sure Cumulative Probability is checked
Check Input constant and enter your z-score in the box
Click OK

The value that Minitab returns will be the area to the left. To find the area to the right, subtract the area to the left from one.

The "twice smaller value" is found by taking the smaller of the two areas and multiplying it by two. Why we do this will become more apparent in later chapters.

Finding Z-Scores (Question 2)

This uses the inverse cumulative probability, which gives you the z-score when you know the area to the left.

Choose Calc / Probability Distributions / Normal
Make sure Inverse Cumulative Probability is checked
Check the input constant radio button
1. If the area you know is the area to the left, enter it into the box
2. If the area you know is the area to the right, subtract it from one and then enter it into the box
3. If the area is some other area, you have to figure out how much is to the left and then enter that into the box.
Click OK

Test Scores (Question 3)

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

Pick the appropriate set of instructions from above, but change the mean to 75 and the standard deviation to 8 before continuing.

Sampling Distributions (Question 4)

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