The distance $\displaystyle d$ to the visible horizon varies directly with the square root of the height $\displaystyle h$

of the observer above sea level. An observer 1.8 m tall can see 4.8 km out to sea when

standing on the shoreline.

I know how to do it but the answers says I'm wrong...

$\displaystyle d \alpha \sqrt{h} $ <--- this is meant to be proportional sign but I can't seem to find it and alpha looks close enough xD

so $\displaystyle d=k*\sqrt{h} $

$\displaystyle 4.8=k*\sqrt{1.8} $

k=3.57771

we found k then:

$\displaystyle d=k*\sqrt{4} $

$\displaystyle d=3.57771 * 2 $

but the answer is like 8. something