What is the range of vision for a normal human eye?

What is meant by the near point of the eye?

Which of the following is true for the eye defect known as hypermetropia (farsightedness)?

The far point of a myopic person is $80 \, cm$ in front of the eyes. What is the nature and power of the lens required to enable him to see very distant objects distinctly?

$A$ $14$ year old student is not able to see clearly the questions written on the blackboard placed at a distance of $5\, m$ from him.
$(a)$ Name the defect of vision he is suffering from.
$(b)$ With the help of labelled ray diagrams show how this defect can be corrected.
$(c)$ Name the type of lens used to correct this defect.

What is meant by the least distance of distinct vision? How does this vary between the very young and old people?