Pulling Trailers Reduce the Gas Mileage

Short Answer

Pulling trailers reduce the gas mileage. Suppose that an unloaded car gets X miles per gallon, and a car towing a trailer gets Y miles per gallon, where X and Y are random variables with a joint density which is bivariate normal with μx=22, σx=2.2, μy=14, σy=3.2 and ρ=.4. If a certain car gets 24 miles per gallon without a trailer, find the probability that it gets at most 15 miles per gallon with a trailer.