Stat 2021 - Project 4 with working Minitab template

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Stat 2021                                                                    Name ___________________________________

Project 4  =  Due 12/16/2013

You may use Minitab, Excel, or a TI-83 or TI-84 calculator to solve these problems. Use this document and fill in your answers. Submit your project in the Project 4 dropbox on D2L by the due date and make sure to include _minitab, _excel, or _TI in your file name as appropriate.

1.  A manufacturer that fills soda bottles periodically tests to see if there is a difference between the mean amounts of soda put in bottles of regular cola and diet cola. A random sample of 14 bottles of regular cola has a mean of 501.6 mL of soda with a standard deviation of 3.9 mL. A random sample of 16 bottles of diet cola has a mean of 498.9 mL of soda with a standard deviation of 5.3 mL. Test the claim that there is a difference between the mean fill levels for the two types of soda using a 0.01 level of significance.  Assume that both populations are normally distributed and that the population variances are not equal.

2.  Temperature by Age? Listed in the table below are body temperatures (°F) of randomly selected subjects from three different age groups. Use a 0.05 significance level to test the claim that the three age groups have the same mean body temperature. (Use Stat – ANOVA – One-Way (Unstacked))

3. A psychology graduate student wants to test the claim that there is a significant difference between the IQs of husbands and their wives. To test this claim, she measures the IQs of 9 married couples using a standard IQ test. The results of the IQ test are listed in the table. Using a 0.05 level of significance, test the claim that there is a significant difference between the IQs of husbands and their wives.

4. Students studying for a state achievement test were asked to keep track of the total number of hours they spent playing video games during the two weeks before the test. In the following table, x is the number of hours spent playing video games (on any type of device) and y is the student’s score on the achievement test (out of 130).

a) Find the equation of the least squares regression line, with coefficients rounded to three decimal places, if necessary: (for example: y = 5.324 + 0.893x)

b) In this situation, the absolute value of the correlation coefficient, r, must be ≥ 0.707 in order to use this least squares regression line to make predictions. Find the value of r. Is it appropriate to make predictions with this line? If so, predict the achievement test score of a student playing 11.5 hours of video games.