Use a series to model the situation in each of the following problems.
Cleo deposited $\$ 1000$ at the beginning of each year for 5 years into an account paying $10 \%$ interest compounded annually. Write a series using summation notation to describe how much she has in the account at the end of the fifth year. Note that the first $\$ 1000$ will receive interest for 5 years, the second $\$ 1000$ will receive interest for 4 years, and so on.