Suppose you have very little knowledge about professional ice hockey, but you want to get a sense of how many goals are scored per game on average and what a typical margin of victory is. You decide to select a sample of games from the current season and record the total number of goals and margin of victory in each game.
a. What are the observational units and variables in this study? Are the variables categorical or quantitative?
b. Describe how you could take a simple random sample of 44 National Hockey League (NHL) games from the current season.
Feeling too lazy to take a simple random sample of games, one of the authors recorded data on all 44 NHL games played between Thursday, December 19, to Monday,December 23, 2013. Th e data are in the file called Hockey on the textbook website.
c. Examine and describe a graph of the distribution of total number of goals in the sample.
d. Based on this graph, do you think it’s valid to produce a theory-based 95% confidence interval based on these data? Explain.
e. Calculate the sample mean and sample standard deviation. Report these along with the appropriate symbols.

f. Determine a 95% confidence interval for the population mean number of goals scored in an NHL game.
g. Interpret what this confidence interval says.