16.The temperature T {in degrees Fahrenheit} of a person during an illness is given by Tin = of +1.2: + ass. where t is the time in days. c. Find Tia) and interpret your results. d. Find T18) and interpret your results. 11A company that produces snowboards. which are seasonal products. forecasts monthly sales for one year to be S = 74.50 + 43.?5cos{%] where S is sales in thousands of units and t is the time in months. with t =1 corresponding to January. How fast are sales changing in September? 13.When the air temperature is a constant 15 degrees Fahrenheit. one formula that meteorologists can use to calculate wind chill temperature is Writs} = 55.1?4- 2.153 - 23.1815. where s is the wind speed in miles per hour and WC is the wind chill in degrees Fahrenheit. Find the rate of change of wind chill when the wind speed is 25 miles per hour. ANSWERS 1. a. 1 b. x = -3, x =5 c. 2. X =0, X =-2, X =2 3. C=4 4. s'(t) =t-1/2 _10t-3 _81-1/3 + 5 5. 14.5 feet per second 6. g'(x) = -6x-3+13x-15/2 7. a. 3 b. oo c. -2 d. 2 e. 4 f. 2 g. -4, 0, 3 8. As time increases, the concentration of the drug is approaching zero milligrams. 9. 3 feet/second; 6 feet/second/second 10. a. f'(x) = 2x1/3 +15e-5x +1 dt b. y = 6cos(2t) - 4 sint 11. y =-8x +5 12. -0.06 mg/hour 13. -00 14. XO 15. -1.09 kilograms/hour 16. a. T(8) =101.8 F ; On day 8 the temperature of the person is 101.8 F. b. T'(8) = -0.4 'F per day; On day 8 the temperature of the person is decreasing by 0.4 'F per day. 17. Sales are increasing by 22.9 thousand units per month. 18. -4.468 'F per mph