1. Section 11.3 Finite Geometric Series

2. A fast-food restaurant introduces a new sandwich
A fast-food restaurant introduces a new sandwich. In the first month, the restaurant sells 50,000 sandwiches. The number of sandwiches sold each month increases by 20%. Assuming this trend continues for one year, how many sandwiches does the restaurant sell during the year?
You may want to make a table to see what’s going on each month
Create a formula, Sn , to denote the number of sandwiches sold by the end of the nth month

3. Now the larger n is, the more difficult the computation is for
We can simplify this expression using a little algebra
Let’s use our new formula to find S12
We can use the same trick to find a formula for the sum of any given finite geometric series

4. The sum of a finite geometric series with a common ratio r and first term a1 is given by
Let’s revisit our fast-food example and suppose that they sell 20% less hamburgers each month for one year, how many total hamburgers will they sell during that year?

5. Find the sums of the following series