The apparent depth of an object in water (as viewed from air) is less than the real depth due to refraction. The relationship is given by:

\(\mu = \frac{\text{Real depth}}{\text{Apparent depth}}\)

where \(\mu\) is the refractive index of water (\(\mu = 1.33\)).

Rearranging for real depth: \(\text{Real depth} = \mu \times \text{Apparent depth} = 1.33 \times 10 \, \text{cm} = 13.3 \, \text{cm}\)