In a certain city the temperature $($in$\backslash$deg F$)$t$$hours after $9$ AM was modeled by the function$$T$($t$)=59-2\mathrm{.}8$t$+0\mathrm{.}43$t$^2-0\mathrm{.}018$t$^3.$Find the average temperature during the period from$9$ AM$$to$9$ PM$.($Round your answer to one decimal place.$)$