The function J{x) - 3.1 VX + 19 models the median height, f(x), in inches, of girls

Chapter 2, Problem 128

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The function J{x) - 3.1 VX + 19 models the median height, f(x), in inches, of girls whoarex months of age. The graph of / is shown. 50 40 10 Girls' Heights Age (months) Source: Laura Walther Nathanson, The Portable Peditltridan for Ptm:Jils a. Describe how the graph can be obtained using transformations of the square root function f(x) - '\IX. b. According to the model, what is the median height of girls who are 48 months, or 4 years. old? Use a calculator and round to the nearest tenth of an inch. The actual median height for girls at 48 months is 40.2 inches. How well does the model describe the actual height? c. Use the model to find the average rate o f change. in inches per mont h, be tween birth and tO months. Round to the nearest tenth. d. Use the model to find the average rate o f change. in inches pe r month, between 50 and 60 months. Round to the nearest te nth. How does this compare with your answer in part (c)? How is this diffe rence shown by the graph?