Answer: white marble: you have a 5/10% chance
Black marble: you have a 5/9% chance
Explanation:
for the white marble you have 5 out 10 because there are half and half then you have to add them all up for the total and not placing it back in the bag there are only 9 left with still 5 black ones so you have a 5 out 9 chance to get a black one