Generally speaking, more houses were built in the later 1900s than the earlier years. In addition there are no figures available for house building in many countries of the world so the average age would be impossible to calculate.
0.5
What??
6 to 1
0.15
quarter to3
4
4:3 is equivalent to 42
sometimes
9:00 to3:00
That will depend on the question which has not been given.
15 to 1
one hour