Because it does not specify that she has to choose one or two from each category all pieces of jewelry can be treated as choices in a combination set.
the formula for a combination is
where n is a total number of choices ( 11 )
and r is number chosen out of those choices (4)
so
C(11,4)= \frac{11!}{4!(11-4)!}
She has 330 possible choices to come home with 4 pieces of jewelry
the formula for a combination is
where n is a total number of choices ( 11 )
and r is number chosen out of those choices (4)
so
C(11,4)= \frac{11!}{4!(11-4)!}
She has 330 possible choices to come home with 4 pieces of jewelry