The average global temperature increase T

left parenthesis in degrees Upper F right parenthesis$($in$$F$)$

is expressed by

Upper T left parenthesis k right parenthesis equals $1\mathrm{.}03$ k ln StartFraction Upper C Over Upper C $0$ EndFractionT$($k$)=1\mathrm{.}03$klnCC$0,$

where

Upper C $0$C$0$

is the preindustrial amount of carbon$$ dioxide, C is the current carbon dioxide$$ level, and k is a constant. Suppose

$12$ less than or equals k less than or equals $2012$k$20$

when C is

tripletriple

the value of

Upper C $0$C$0.$

Use$$

Upper T left parenthesis k right parenthesisT$($k$)$

to find the range of the rise in global temperature T$.$