$?$ Exercise $4\mathrm{.}7\mathrm{.}3$

Suppose the island $is1mi$ from shore, and the distance from the cabin $to$ the point $on$ the shore closest

$to$ the island $is15mi.$ Suppose a visitor swims $at$ the rate $of2\mathrm{.}5mph$ and runs $at$ a rate $of6mph.$ Let

$x$ denote the distance the visitor will run before swimming, and find a function for the time $it$ takes

the visitor $to$ get from the cabin $to$ the island.

$T(x)=$

Hint

The time $T=T_{\text{r}\text{u}\text{n}\text{n}\text{i}\text{n}\text{g}}+T_{\text{s}\text{w}\text{i}\text{m}\text{m}\text{i}\text{n}\text{g}}.$