Suppose we wish to know if there is a difference in choice of model based on comfort between population groups classified as under-weight, normal weight,  or over-weight. To make this determination 600 people were classified in one of the three weight classes and then asked to select the most comfortable seat. The results are summarized in the following table.

                                         Seat Preference

Weight Class:      Model A         Model B         Model C

Under-Weight           100             40                    50

Normal-Weight           90              70                    60

Over-Weight              40              60                    90

A) Write an appropriate null and alternative hypothesis.

B) Compute the expected frequency for the first cell in row one.

C) Test the null hypothesis at the 0.05 significance level. Make a decision  to reject or fail to reject the null based on the p-value.

D) Draw a conclusion about the relationship between weight and type of seat based on comfort.