a taxi company is trying to decide whether to purchase Brand A or Brand B tires for its fleet of taxis. to help arrive at a decision, an experiment is conducted using 12 tires of each brand, the taxis are run until they wear out. the results are as follows

Brand A X_{1= 37,900 km ^{S1 = 5100km}}

_{Brand B X2 = 39,800 km S2 = 5900km}

_{assuming that the populations to be approximately normal}

_{A) is there a deference in the two brands of tires}

_{b) is the standard deviation of the distance of brand A tires smaller,}

_{show all your working to prove your answers}