The near point and far point of a normal human eye are respectively:

The near point and far point of a person are $40\,cm$ and $250\,cm$ respectively. Determine the power of the lens he/she should use while reading a book kept at a distance of $25\,cm$ from the eye $..........D$

$A$ person cannot see objects beyond $3 \, m$. What should be the focal length of the lens required to see objects at $12 \, m$?

If the far point of a short-sighted person is $400 \ cm$, then the power of the lens required to enable him to see very distant objects clearly is

$A$ person can see clearly only up to a distance of $25 \, cm$. He wants to read a book placed at a distance of $50 \, cm$. What kind of lens does he require for his spectacles and what must be its power?

$A$ lens of power $0.66 \ D$ is used to correct myopia. What is the far point of the eye in $cm$?