Question

a bag contains 4 yellow marbles 6 red marbles 5 blue marbles 6 white marbles and 4 black marbles what is the theoretical probability of pulling a white marble from the bag

Answer 1

$|\Omega|=25\\ |A|=6\\\\ P(A)=\dfrac{6}{25}$

Answer 2

4 Yelllow + 6 Red + 5 Blue + 6 White + 4 Black = 25 Marbles total
There are 6 white marbles, so you have a 6/25 chance of getting a white marbles.