Abox contains 3 blue and 2 red marbles while another box contains 2 blue and 5 red marbles. a marble drawn at random from one of the boxes turns out to be blue. what is the probability that it came from the first box?

First add all the numbers together to get the total number of marbles which would be 12 then make a fraction 3/12. Which can be simplified to 1/4 which if needed can be changed to a percentage of 25%. So your answer is either 1/4 or 25% depending on how your teacher would like it written.