Answer
For the person in the brightly lit outdoors, the reflected light generally dominates the light transmitted through the window from the interior of the house, making it hard to see into the dark room.
Work Step by Step
A window both transmits and reflects light. A pane of window glass transmits about $92\%$ of the incident light, and reflects about $8\%$ . This is discussed on page 523 and covered in problems 41 and 42 in this chapter.
The person outside, in the daylight, sees $8\%$ of the daylight reflected back and $92\%$ of the room's light transmitted out. The intensity of the reflected light might exceed that of the transmitted light, making it difficult to see into the house.
On the other hand, the person inside the dark room receives $92\%$ of the transmitted outdoor light and only $8\%$ of the reflected dim inside light. S/he can easily see out.
