А A pool of water of refractive index 4/3! is 60cm deep. Find its apparent
depth when viewed vertically through
air.

Apparent depth = 45 cm

Explanation:

The refractive index of water in a pool, n = 4/3

Real depth, d = 60 cm

We need to find its apparent  depth when viewed vertically through  air. The ratio of real depth to the apparent depth is equal to the refractive index of the material. Let the apparent depth is d'. So,

So, the apparent depth is 45 cm.