English ambiguities

I include two examples of weird ambiguities in English. I've personally run across each of these at least once.

1. Jennifer is 18, has two brothers, aged 21 and 27. She has no other siblings. Does Jennifer have a younger brother?
   
   
2. Ten marbles were initially painted black. One marble was re-painted white. An hour later, every other marble was re-painted red. How many marbles were re-painted red?