A university wants to investigate how much its students spend on textbooks each semester. Since all students must purchase their materials through the campus bookstore, a random sample of 15 student
accounts is selected, and the averagą dollar amount spent on textbooks is calculated.
Which of these circumstances would make it inappropriate to use this sample to calculate a 95%
confidence interval for the mean amount spent on books by students at this university?
The standard deviation of the textbook costs is below $30.
The standard deviation of the textbook costs is larger than $100.
A stem-and-leaf plot of the textbook costs shows a roughly symmetric distribution
A histogram of the textbook costs is calculated and shows a slight skew to the right.
A boxplot of the textbook costs shows two students whose amounts would qualify as outliers,