I have seen this question asked a few times on SO - but the answer always seems to be roughly the same:
/Users/myName/Library/Application Support/iPhone Sim
I think 4.2 is your version of iOS simulator, because at that path you must select you simulator version. Under that, there must be a folder called Applications, under that there are some intersted named folders(i thing these names are MD5 or something else) and each of these folders stand for an individual application. Find the folder related to the application you are looking for, under Documents folder there must be the database file