Question

The set S represents the elements present in sugar.

S = {carbon, hydrogen, oxygen}

The set C represents the elements present in carbon dioxide gas.

C = {carbon, oxygen}

How many elements are in the set S ∪ C?

A 1
B 2
C 3
D 5

Answer 1

Combine sets S and C to get


S U C = {carbon, hydrogen, oxygen, carbon, oxygen}


then remove duplicates to get


S U C = {carbon, hydrogen, oxygen}



So there are 3 elements in set S U C, so the answer is choice C

Answer 2

Notice how set C is a subset of set S


So S U C = S