Can somebody please help with this? (Slope)

Barbara deposited $300 in the bank. if the bank pays her simple interest at the rate of 4 percent per year, how much money will she have in her account at the end of 9 months?

Is the response to the survey question "did you smoke in the last week question mark "response to the survey question "did you smoke in the last week? " a discrete random variable, a continuous random variable, or not a random variable?

How many revolutions will a car wheel of diameter 28 in. make over a period of half an hour if the car is traveling at 60 mi/hr? the final answer is supposedly 21,609 but i have no idea how to get that, show work : )