Question

Tom does not really want to give away blue marbles and would like to change the probability that he chooses a blue marble to 1/10. How many marbles that are not blue could he add to the bag so that the probability of choosing a blue marble becomes 1/10?

Answer 1

9

Explanation:

if one marble is blue and 9 are other colors than its a 1/10 chance of getting a blue marble