Sulfur   compounds cause “off odors” in wine, so winemakers want to know the   odor threshold, the lowest concentration of compound that the human nose can   detect.  The odor threshold for dimethyl sulfide (DMS) in trained   wine tasters is about 25 micrograms per liter of wine (mg/l).  The   untrained noses of consumers may be less sensitive, however.  Here   are the DMS odor thresholds for 10 untrained students:    31      Are untrained students less   sensitive on the average than trained tasters in detecting “off   odors” in wine?  The units are micrograms of DMS per liter of   wine (mg/l).  Assume that the odor threshold for untrained noses in   Normally distributed with standard deviation = 7mg/l.  Is there   evidence that the mean threshold for untrained tasters is greater than 25   mg/l?