A person wears glasses with a power of -2.5 D . Is the person...

The power of the lens is given as $P = -2.5 \text{ D}$.

Since the power is negative, the lens is concave. A concave lens is used to correct nearsightedness (myopia).

The focal length of the lens is given by $f = \dfrac{1}{P} = \dfrac{1}{-2.5} \text{ m} = -0.4 \text{ m} = -40 \text{ cm}$.

For a nearsighted eye, the corrective lens forms a virtual image of an object at infinity at the person's far point.

Using the lens formula $\dfrac{1}{v} - \dfrac{1}{u} = \dfrac{1}{f}$ with $u = -\infty$, we get $v = f = -40 \text{ cm}$.

The far point of the person without glasses is $40 \text{ cm}$.