Average bedroom size in a four bedroom house?

Answer 1

It depends on what part of the country you live in. The porportions are more important - i.e. in a 5000 sq ft house average bedroom sizes will be larger than in a 2000 sq.ft. house. There are minimums set by the ICC (used to be called the uniform building code).

Answer 2

The cost of an apartment will vary enormously, depending on where it is located and on what kind of condition it is in, among other considerations, so there really is not enough information in the question to give any kind of meaningful answer.

Answer 3

It varies immensely. There are places that a 3 room apartment's rent would be somewhere around 50$ a month, while other places can get to 10,000$ a month. Specify more next time.