Hypermetropia can be corrected by using a convex lens. A convex lens converges the incoming light such that the image is formed on the retina.

An object at 25 cm forms an image at the near point of the hypermetropic eye. Here, near point is 1 m.

Given, Object distance, u = –25 cm

Image distance, v = –100 cm

From lens formula, $\frac{1}{\mathrm{v}}–\frac{1}{\mathrm{u}}=\frac{1}{\mathrm{f}}$ 

$\frac{1}{–100}–\frac{1}{–25}=\frac{1}{\mathrm{f}}$

Focal length, f = 100/3cm = 1/3m

Power, $\mathrm{P}=\frac{1}{\mathrm{f}}=\frac{1}{{\displaystyle \frac{1}{3}}}=3\mathrm{D}$