Answer:
46 marbles is the minimum number of marbles
Explanation:
Firstly, if it results that he went on picking 45 times on a stretch, it is possible that he picks all as green marbles
However, on the 46th pick, it is sure that he would have exhausted all the green marbles and picked another marble type
Hence, what we are saying is that by his 46th pick, it is sure that he would have picked a second marble type