the howel family just welcomed home a new baby and now they are looking for ways to save money. they have purchased an eco-luxury low flow shower head for $50 which uses 1.5 gallons of water per minute. the family uses the shower about three hours a day and pays $0.004 per gallon of water.

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?