Calculate Focal Length to Reduce Viewing Distance to 25cm

[v_pino]

Homework Statement

A patient is unable to see objects closer than 1m from the eye. Calculate the focal length of the converging lens which is required to reduce this to 25cm.

Homework Equations

Lensmaker's equation: 1/u + 1/v = 1/f

u= distance from object to lens
v= distance of image to lens
f = focal length

The Attempt at a Solution

I tried using the above equation by substituting in u=1m, v=0.25m. But that doesn't help. The solution should be 33cm.

 

[rl.bhat]

Here the image is virtual.
So the formula should be
1/u - 1/v = 1/f.