The sample space is {1,2,3,4,5,6}
A. The only perfect squares in the sample space are 1 and 4.
That's because 1 = 1² and 4 = 2².
That's 2 ways out of 6 ways that a perfect square number can
be rolled. "Out of" means "over", so the probability is
2 over 6 or 2/6 and that reduces to 1/3.
B. The only prime numbers in the sample space are 2,3 and 5.
That's 3 ways out of 6 ways that a prime number can be
be rolled. "Out of" means "over", so the probability is
3 over 6 or 3/6 and that reduces to 1/2.
Edwin