I need help answering this question:

A parallel computer consists of 11 processors and 11 memory modules. During; a step, each processor sends a memory request to one of the memory modules. A memory module can satisfy one request in a step; modules that receive more than one requests will satisfy one request. and discard the rest. Assuming that, each processor chooses a memory module independently and uniformly at random, what is the expected number of processors whose requests are satised? Use the approximation (1 1/12)" x 1 / e if necessary