How many different codes are possible?

Question

Assume that X = { A, D, E} and Y = { 7, 4, 6, 2}. A code consists of 2 different symbols selected from X followed by 2 not necessarily different symbols from Y.

Answer 1

First two symbols has 6 combinations.

The third and fourth symbols each has 4 possibilities.

 

So there are 6*4*4 = 96 different possible codes.