Answer:
a You must choose at least 3 marbles
Step-by-step explanation:
If the probability is equally likely that you will choose a red or blue marble (1/2)
Then the marbles will need to be the same size or you will know which the color of the marble by the size.
There needs to be the same number of marbles, or you will be more likely to pick the color with more marbles of that color
If you look, you will pick the color of the marble you want.
The probability is determined by the number of marbles in the bag, not by the number you choose
