A bag contains 2 red, 3 green and 5 blue balls A ball is drawn, observed and put again in the bag. Find the probability of getting all colours different.
My teacher's solution:
2/10 × 3/10 × 5/10 × 3! × 2
I don't get why that last 2 was necessary
Edit: balls are drawn 3 times

Yes, you have to delete the last 2.
Maybe the teacher wanted to just put $3 \cdot 2$ and not $3! \cdot 2$
