A far sighted person cannot focus distinctly on objects closer than "1m" What is the power of lens that will permit him to read from a distance of "40cm"

A person cannot see distinctly any object placed beyond 40cm from his eye. Find the power of lens whicTFwill enable him to see distant stars clearly is?.

A farsighted person cannot see objects placed closer to 50 cm. Find the power of the lens needed to see the objects at 20 cm.

A farsighted person cannot see objects placed closer to 50 cm. Find the power of the lens needed to see the objects at 20 cm.

A farsighted person cannot see objects placed closer to 50 cm. Find the power of the lens needed to see the objects at 20 cm.

A short sighted person can see distinctly only those objects which lie between 10 cm and 100 cm from him. The power of the spectacle lens required to see a distant object is