Question

A bag contains 1 green marble, 2 yellow marbles, 4 blue marbles, and 5 red marbles. How many blue marbles would you need to add the original bag of marbles to make the probability of drawing a blue marble 1/2?

Answer 1

You need to add 4 more blue marbles, then there will be 8 blue marbles and the probability of drawing a blue one will be 8 out of 16 (the total of marbles)

And

8/16 = 1/2