A man sits in an optician's chair looking into a plane mirror which is 2 m away from him and views the image of a chart which faces the mirror and is 50 cm behind his head. How far away from his eyes does the chart appear to be?

Distance between man and chart = 50 cm = 0.5 m

Distance between image of the chart and mirror = 0.5 m + 2 m = 2.5 m

The image of the chart will form at a distance of 2.5 m behind the mirror, because the image formed by a plane mirror, is at the same distance behind it as it is between the object and the mirror.

Thus, 

Distance between the chart's image and the eye = Distance between man and the mirror + Distance between mirror and the image of the chart = 2 m + 2.5 m = 4.5 m.