Question

tom does not reallt want to give away blue marbles and would like to change the probability that he chooses a blue marble to one tenth. how many marbles that are not blue could he add to the bag so that the probability of choosing a blue marble becomes one tenth.

Answer 1

We don't know how many of ANY color are in the bag right now, so there's no way to calculate an answer.

What Tom has to do is make sure that the number of marbles that are NOT blue is NINE TIMES the number of blue ones in the bag.