Are the elementary events:
4 because you'll either pick a red, green, white or yellow ball?
are they 7 because there are 3 red, 2 green, 1 white and 1 yellow balls?
Also, if the question is " Box contains 3 red, 2 green, 1 white and 1 yellow balls. You draw 1 ball, remember its color and return it to the box, then you draw another one. How many elementary events are there?" does that mean there will be even more elementary events because we'd to take into consideration the second drawn ball?