Jamie has a bag containing purple, pink, yellow, and blue marbles. There are a total of 40 marbles in the bag. Jamie randomly selects a marble from the bag and then puts it back. He repeats this process 420 times. If Jamie selected a pink marble 10 times, what is a good prediction of the number of pink marbles in the bag?

1 pink marble

Step-by-step explanation:

If Jamie selected 10 times the pink marble in a total of 420 tries, we can assume that the proportion of pink marble in the total number of marbles is:

10 / 420 = 1/42

So to predict a good number of pink marbles in the total 40 marbles, we just need to multiply the 40 marbles by the proportion found above:

pink marble = 40 * (1/42) = 0.9524

As this number needs to be a whole number, a good assumption is that there is 1 pink marble in the 40 marbles.