Hey guys, I got this optics problem I don't understand. I drew out the diagram but still don't understand which forumla to apply. I am extremely confused over why the index of refraction for water is given, I'm not sure where that comes in.

A person stands beside his swimming pool, which is full of water. His eyes are at a level 1.6 m directly above the edge of the pool, and looks directly across the pool which is 7 m wide. Light from the bottom corner opposite him arrives at his eye in such a direction that the apparent depth of water, h, is 0.3 m. If the Refractive Index of water is 4/3, calculate H, the actual depth of the pool.

Thank you in advance.

-Kurzick Mushroom