Question

The price of products may increase due to inflation and decrease due to depreciation. Derek is studying the change in the price of two products, A and B, over time. The price f(x), in dollars, of product A after x years is represented by the function below: f(x) = 12500(0.82)x Part A: Is the price of product A increasing or decreasing and by what percentage per year? Justify your answer. (5 points) Part B: The table below shows the price f(t), in dollars, of product B after t years: t (number of years) 1 2 3 4 f(t) (price in dollars) 5600 3136 1756.16 983.45 Which product recorded a greater percentage change in price over the previous year? Justify your answer. (5 points)

Answer 1

For product A, the product is increasing, for the bigger the number you plug into x (due to the fact that the numbers become bigger because of the time: year 1, year 2, etc)
Product A is 82% change rate, while 
product B is 983.45/4 = 245.8625,  1756.16/3 = 585.3867
Product B is 245.8625/585.3867
product B is 42% change rate

Product A change rate is higher than Product B by 40%

hope this helps