Help me please i don’t understand

Do graduates from uf tend to have a higher income than students at fsu, five years after graduation? a random sample of 100 graduates was taken from both schools. let muf be the population mean salary at uf and let mufsu be the population mean salary at fsu. how should we write the alternative hypothesis?

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

There are three bags: a (contains 2 white and 4 red balls), b (8 white, 4 red) and c (1 white 3 red). you select one ball at random from each bag, observe that exactly two are white, but forget which ball came from which bag. what is the probability that you selected a white ball from bag a?