A small air bubble is inside a glass cube of side 15 cm. When seeing from the top face, the bubble a

A small air bubble is inside a glass cube of side 15 cm. ,When seeing from the top face, the bubble appears at a distance of 5 cm, and if seen from the opposite face it appears at 7 cm. ,Refractive index of glass is,
(1) 5/4,
(2) 3/2,
(3)5/2,
(4) 5/3,

#apparentdepth