So we have the equation:
[tex]y=-0.37x^2+6.15x+52.3[/tex]Where x represents the hours passed after 5 am and y represents the temperature in degrees Fahrenheit. We are being asked about the temperature at 9 am so we need to express 9 am in terms of hours passed after 5 am. Since there's a difference of 4 hours between this two times then we must use x=4 and the result of substituting x by 4 in the former equation will give us the temperature we are looking for:
[tex]y_{(4)}=-0.37\cdot4^2+6.15\cdot4+52.3=70.98[/tex]So the temperature in october at 9 am is 70.98°F so the best approximation would be option C, 71°F.
