Suppose $f(2)=8$ and $f(6)=18.$ The average rate $of$ change for this function $in$ the

interval $x=2$ and $x=6is$:

$a.2\mathrm{.}5$

$b.14\mathrm{.}66$

$c.2iff(3)=10$

$d.$ Cannot $be$ determined.