A recently opened bottle of wine will smell "off" if sulphur compounds are sufficiently concentrated. It is of interest to winemakers to determine the "odour threshold", i.e., the minimum concentration at which the human nose can detect these odours. For specialist wine tasters the threshold for dimethyl sulphide (DMS) to turn the nose is about 25 microgrammes per litre (g/L) of wine. The average wine consumer may be less sensitive. The data file DMS.csv contains observations of odour thresholds (g/L) obtained from a class of 10 third-year biochemistry students.

(a) To what extent is it reasonable to treat "a class of 10 biochemistry students" as a representative sample of wine consumers? Provide 2 brief reasons to support your answer. From now on, assume that it IS reasonable to treat the data in DMS.csv as coming from a random sample of wine consumers and that relevant statistical conditions and assumptions have been met.

(b) Use RStudio to calculate a 90% confidence interval for the mean DMS odour threshold among wine consumers.

(c) Using the interval calculated in part (b), evaluate a claim that wine consumers are on average just as sensitive to DMS as trained wine tasters.