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Some water sports are expensive. People with larger incomes are more likely to participate in such a sport. The number of people N (measured in thousands) who engage in a particular water sport can be described by the function N(x) = 0.15x- - 3.11x + 106.25, where x is the mean income (measured in thousands) and x 2 20. Use this information to answer the following problem. Find N(20), N(40), N(60), N(80), and N(100). N(20) = thousands of people