The president of a small manufacturing firm is concerned about the continual growth in manufacturing costs in the past several years. The data series of the cost per unit for the firms leading product over the past eight years is as follows: Year Cost/Unit ($) Year Cost/Unit ($) 1 18.00 5 21.10 2 20.00 6 25.20 3 23.00 7 26.20 4 22.40 8 31.20