Answer:
Step-by-step explanation: So theres 10 marbles total in the bag. 5 is one half of 10 so the probability to get a blue marble is 5/10 or 1/2 and the probablility of getting an orange one is 1/10 so you have to first get lucky and get that 5/10 chance, and then get even more lucky and get the 1/10 chance and so I believe that it would be 1/20