Step 1 :Given that Christian buys 9 cups of coffee per week, with each cup costing $4.05, the total amount he spends on coffee each week is \(9 \times 4.05 = 36.45\) dollars.
Step 2 :The annual interest rate for the annuity is 2.8%, which is equivalent to 0.028. Since there are 52 weeks in a year, the weekly interest rate is \(0.028 / 52 = 0.0005384615384615384\).
Step 3 :Christian plans to deposit the amount he would spend on coffee into the annuity for 14 years. Since there are 52 weeks in a year, the total number of periods is \(14 \times 52 = 728\) weeks.
Step 4 :We can now calculate the future value of the annuity using the formula: \(FV = P \times [(1 + r)^{nt} - 1] / r\), where FV is the future value of the annuity, P is the payment per period, r is the interest rate per period, n is the number of periods, and t is the time in years.
Step 5 :Substituting the given values into the formula, we get: \(FV = 36.45 \times [(1 + 0.0005384615384615384)^{728} - 1] / 0.0005384615384615384\).
Step 6 :Solving the equation gives us the future value of the annuity, which is approximately $32,477.79.
Step 7 :Thus, if Christian deposited the amount he would spend on coffee into an ordinary annuity instead, he would have \(\boxed{32,477.79}\) dollars in the annuity after 14 years.