Thomas wants to compare the mean concentration of carbon monoxide (CO) on residential versus commercial streets, since these differ in terms of car traffic. In each of three neighborhoods of Montral (named A, B, and C below), he randomly chooses four locations for each type of street, for a total of 24 observations (2 street types x 3 neighborhoods x 4 locations). At each location, he measures CO concentration in the air over a period of 10 hours (8:00 AM-6:00 PM), and obtains the following data (in ppm/h).

5 - l.,.,.,.0120905 0.,.,.,408060.2 l.,.,.,.ll41512 Sire\" mm mm 21 1.1 3.121' -\" lO-a) Draw a graph that gives insight into the possible presence of an interaction between the two classification factors. Do you suspect the presence of an interaction? Explain why