(2 points) (Exercise 2.16) It is known that an investment of $1500 will accumulate to $2800 at the end of 11 years. If it is assumed that the investment earns simple interest at rate i during the 1st year, 2i during the 2nd year,..., 1li during the 11th year. find i. n(n+1) (Hint: 1 + 2 + +n= -) 2 i = %