About 42 lbs.
A bushel of apples weights about 42 pounds and it will yield 20-24 quarts. But it also depends on the size and weight of the apples. Here is a link that might help:
You can't actually get a count of the number of apples in a bushel. Bushel is the size of the basket and if you have small apples, it will hold more, large apples will be less.