Answer
a) concave
b) $f=-2.2m$
Work Step by Step
(a) We know that the concave lens can produce the image of a distant object within the person's far point, which allows him to focus upon it.
(b) We know that
$\frac{1}{f}=\frac{1}{d_{\circ}}+\frac{1}{d_i}$
We plug in the known values to obtain:
$\frac{1}{f}=\frac{1}{\infty}+\frac{1}{-2.2m}$
This simplifies to:
$f=-2.2m$
