A set S is defined as S ={ 2, 3, 5, 8, 12 , 13 , 18, 21}. Two distinct numbers x and y are chosen at random from the set A?

Q1. Find the probability that x^y is even.
a. 1/2
b. 1/3
c. 1/4
d. 1/6

Q2. Given that x is a prime number, then the probability that the product xy is a perfect square, is
a. 1/14
b. 3/28
c. 1/7
d. 3/16

Q3. If a = (x + y) and b  = (x – y), then the probability that (a^2 – b^2)/4 is an even number is
a. 6/7
b. 11/14
c. 5/7
d. None of these