A bag contains 12 blue, 5 red and 3 green marbles. Amy selects a marble and then returns it to the bag before selecting a marble again. If Amy selects a blue marble 4 out of 20 times, what is the experimental probability that the next she selects will be blue?

Answer 1

there are 12 + 5 + 3 = 20 marbles in the bag.

We do an experiment to find out how many are blue

call the probability of a blue one x

She picks blue 4 out of twenty times, which is 20/100 = 0.20

Her fingers must reject blue because one would expect 12/20 = 0.60