1)A taxi company in a large city put a new type of tire with a special tread on a random sample of 50 cars, and the regular type of tire on another random sample of 50 cars.After a month, the gas mileage of each car was measured.

a)Is this a randomized experiment or an observational study?

b)Assume that one of the samples had noticeably better gas mileage than the other.Could this result be due to confounding?Explain.