Question

The finite sequence whose general term is an = 0.17n2 - 1.02n + 6.67 where n = 1, 2, 3, ..., 9 models the total operating costs, in millions of dollars, for a company from 1991 through 1999. find
a. $21.58 million
b. $27.4 million
c. $23.28 million
d. $29.1 million

Answer 1

Calculate for the values of the terms by substituting 1 to n for 1991, 2 for 1992, 3 for 1993, and so on up to 9 for 1999.

We may opt to solve for the A for the 9 terms such as below.

n = 1.
  A₁ = 0.17(1²) - 1.02(1) + 6.67 = 5.82
  A₂ = 0.17(2²) - 1.02(2) + 6.67 = 5.31
  A₃  = 0.17(3²) - 1.02(3) + 6.67 = 5.14
 A₄  = 0.17(4²) - 1.02(4) + 6.67 = 5.31
 A₅  = 0.17(5²) - 1.02(5) + 6.67 = 5.82
A₆  = 0.17(6²) - 1.02(6) + 6.67 = 6.67
A₇  = 0.17(7²) - 1.02(7) + 6.67 = 7.86
 A₈  = 0.17(8²) - 1.02(8) + 6.67 = 9.39
 A₉ = 0.17(9²) - 1.02(9) + 6.67 = 11.26 

The sum of these values is $62.58. The answer is not among the choices.