Did you read my tips on how to study and learn Stat 2000?  If not, here is a link to those important suggestions:

Did you read my Calculator Tips?  If not, here is a link to those important suggestions:

Don't have my book?  You can download a free sample containing Lesson 3 at my website here:

Do note that every time you exit a question in StatsPortal, the next time you return to it, the data may very well change.  Do not press the "back-up" button on your browser in a question.  That, too, will change the data.  When you are prepared to actually do a question, open the link, keep it open, and do not close it until you have submitted your answers.  There is also some debate whether even pressing "Save Answers" locks the data in place.

You should also have already downloaded the JMP statistical software which was provided with either one of the course options for StatsPortal as mentioned in your course outline.

Make sure you have gone through Assignment 0 completely to learn how to use the interface.  I also suggest you print out a copy of question 8 in Assignment 0 (Long Answer Questions - Part 3) so that you have the steps for saving and uploading files into the HTML editor in front of you.

This is a good overview of the concepts I teach in Lesson 1.  Especially look at my questions 6, 7 and 8.  Use the Inverse-Square Relationship I introduce in question 8 to answer parts (c) and (d).

Just like question 2 above.

Yet more of the same.  To do part (c) more easily, read my part of Lesson 3 talking about "The Relationship between the Alternative Mean and the Power of a Test."

This is just a matter of typing your explanations into the box provided.  Make sure you click the HTML Editor link below the textbox before you type anything in.  This is like what I discuss at the start of Lesson 3 where the Type I error is "saying someone does not have cancer when they actually do."  Note that they also want you to describe the consequences of each error.

This is a standard hypothesis test question where they have you do all five steps eventually, as taught in Lesson 2 of my book.

This question should be done by hand (i.e. with your calculator, not with JMP).  Use the Stat Mode on your calculator to compute the Mean and Standard Deviation.  Check the Appendix at the back of my book to learn how to use the Stat Mode on your calculator.  Here is a link to a digital copy of that appendix:

Part (c) is introducing a key concept about changing the units in data.  Be sure to read the "Effect of Changing Units on Centre and Spread" section of my book in Lesson 1 and see questions 17 and 18 for examples.  As they say, once you know the mean and standard deviation from parts (a) and (b), you can convert them into the mean and standard deviation for part (c) using the conversion formula they gave you at the start.  But do it properly!  Remember, you apply the formula differently depending on whether you are converting a measure of centre or a measure of spread.

For part (d) , consider this:  Let's say you are taking a course, and your average mark so far is 65.  What will happen to your average if you score higher on the next test?  What if you score lower on the next test?  What would you have to get on the next test to have your average stay 65?

For part (e), having decided what that ninth score must be in part (d), how much does that score deviate from the mean? If that is a larger deviation than the standard deviation you computed earlier, you have increased the overall standard deviation; if it is the same amount of deviation as earlier, you have not changed the standard deviation at all; if it has a smaller deviation, you have decreased your overall standard deviation.

This should be done both by hand (i.e. just using your calculator) and with JMP.

Click the HTML Editor link below the textbox before you start typing any answers in.  To type in the formula you are using and to show your numbers subbed into the formula click the button in the textbox that looks like the Sigma Summation symbol.  Then click the various buttons to make your fractions and enter the symbols.  Note, on my computer at least, when I click this Sigma button, the pop-up screen to enter the math equation gets hidden behind my webpage, so I have to minimize the StatsPortal screen in order to see the equation editor window.

Part (a) is fundamental.  See my discussion in Lesson 1 on why Inferences for the Mean are robust.

Part (b) is using an unusual level of confidence.  See my question 10 in Lesson 1 for an example.  Note that they want you to explain how you get z*.

Part (c) is standard.  I show you how to interpret a confidence interval in Lesson 1.

Note that you already know the z* critical value for part (d).  You used it in part (b).  You can use the Equation Editor as I mentioned above to write the formula work you are doing.

Parts (e) and (f) are standard P-value stuff.  I show you how to interpret a P-value in Lesson 2, question 6.

Part (g):  First, enter the data into JMP manually: Click the "New Data Table" icon on the toolbar at top left in the JMP home screen.  You are automatically taken to an empty spreadsheet with one column. Double-click "Column 1" and change its name to "Waiting Time", or right-click "Column 1" and select "Column Info" and type in the name "Waiting Time" and click OK.

Now just type in the various Waiting Time values in the cells using your "Tab" or down arrow button to move to each proceeding cell.  You can also hit "Enter" after each piece of data to enter it and move to the next cell.

Once you have entered all the data down your columns, you are ready to test the hypothesis and make your confidence interval.  In the toolbar at the top, select Analyze then select Distribution.  In the "Select Columns" part of the pop-up window, click the column you want to analyze ("Waiting Time" in this case) to highlight it, and click the Y, Columns button.  You should see the "Waiting Time" column appear in the section to the right of the "Y, Columns" button.  Click OK.

It now opens yet another pop-up window called "Distributions" where a histogram should appear.  Your histogram appears sideways.

To get JMP to make confidence intervals and test hypotheses for the mean:
To get a confidence interval , click the red triangle next to variable "Waiting Time" directly above the histogram to get a drop-down list and select "Confidence Interval".  In the pop-up window that appears, select "Other" (even if the level of confidence you desire is in the list) and type in the level of confidence you want (in decimal form, so 97%, for example, is 0.97).  Make sure "Two-sided" is selected.  You are given a value for sigma, the population standard deviation, so click the "Use known Sigma" checkbox.  Click OK.  You will get another pop-up window where you can type in your known value for sigma.  A Confidence Intervals table will appear in your output screen at the bottom.  Your lower and upper limits are shown under "Lower CI" and "Upper CI" in the Mean row.  These answers should agree with your computed answers in part (b) above.

To test a hypothesis, click that same red triangle you used to make a confidence interval and select "Test Mean".  Type in the value the null hypothesis believes the mean to be and type in the known value of sigma in the box that says "Enter the True Standard Deviation to do a z-test ...".  Click OK.  A "Test Mean =  Value" table appears in your output where, among other things, JMP gives you the test statistic and three probability values.  Those three probabilities are the P-value for the three possible alternative hypotheses.  JMP will use a z statistic since you gave it a sigma value.  It is up to you to know what the correct alternative hypothesis is, and so whether the test is two-tailed, upper-tailed, or lower-tailed.

• Prob > 'z' is the two-tailed P-value.
• Prob > z is the upper-tailed P-value.
• Prob < z is the lower-tailed P-value.

JMP's answer for the P-value should agree with what you calculated yourself in part (e).

Don't forget to answer part (h) in the text box!