Are all these answers correct? samples and population in mathematics. i really need it.

Me. drysdale earned 906.25 in interest in one year on money that he had deposited in his local bank if the bank paid an interest rate of 6.25% how much money did mr. drysdale deposit

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population, find the population standard deviation, o.79828588912497

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?