The least distance of distinct vision required = 25 cm. ∴ for the person to see an object clearly at 25 cm from the eye, the image must be formed at 75 cm on the same side of lens, at his near point. ∴ U = 25 cm; V = -75 cm (image should be virtual) thus \(\frac{1}{f}\) = \(\frac{1}{v}\) +\(\frac{1}{u}\) = \(\frac{1}{75}\) + \(\frac{1}{25}\) = \(\frac{-1 + 3}{75}\) = \(\frac{2}{75}\) ∴f = \(\frac{75}{2}\) = 37.50cm.