Luis bought stock at $68.20. The next day, the price increased $19.20. This new price changed by −2 3/4 % the following day. What was the final stock price, rounded to the nearest cent? Is your answer reasonable?

You just purchased two coins at a price of $670 each. because one of the coins is more collectible, you believe that its value will increase at a rate of 7.1 percent per year, while you believe the second coin will only increase at 6.5 percent per year. if you are correct, how much more will the first coin be worth in 15 years?