Question 4 25 points Consumer Reports tested 14 brands of va

Question 4: [25 points] Consumer Reports tested 14 brands of vanilla yogourt and found the following numbers of calories per serving: 160 200 220 230 120 180 140 130 170 190 80 120 100 170

(a) Use R to produce a QQ-plot of the number calories per serving in vanilla yogourt. Based on this QQ-plot, does it appear reasonable to assume that the number calories per serving in vanilla yogourt is normally distributed? Discuss.

(b) Use R to compute the sample mean and the sample standard deviation of the number calories per serving for these 14 brands.

(c) Based on your answer for parts (a) and (b), give a 95% confidence interval for the mean number calories per serving. Do not use R for this part.

(d) A diet guide claims that you will get an average of 120 calories from a serving of vanilla yogourt. Based on part (c), is this a reasonable assertion? Discuss.

Solution