This question falls under the category of different things getting distributed to different people.
Given 3 different ice creams there are 23
of selection possible. This is because none of them can be selected(nC0
), one of them selected(nC1
) , two of them selected(nC2
) and three of them selected(nC3
). Here n =3, thus there are 23
As per the question at least one of them has to be selected. Therefore nC0
selection has to be excluded, 23
Thus for all the items the final product becomes as , (23
-1) = 315.