Geometrical Optics-13

Correct answer is 45 cm.

The system is shown in the figure, fist image will formed after refraction from lens, then rays will be get reflected on the mirror, as the primary image by lens will act as a virtual object for plane mirror.
The mirror then form a real image for that virtual object which pass through the water (will behave like a slab which going to produce a shift) and the final image is formed at bottom of the container.
All you have to find is the distance between the bottom of the container and pole of the plane mirror.

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