Number Sets

An intersection of two sets is defined as the set of elements that are members of both sets. The correct answer is the pair of sets that has no overlap.

Rationals are defined if a and b are integers. The irrationals are defined as any real number that is not rational. By definition a number cannot be both rational and irrational.

Prime numbers are divisible only by 1 and themselves. Even numbers are defined as integer multiples of . A number common to both sets is .

Natural numbers are the counting numbers, while the integers are all the naturals and their opposites. There are many elements common to both sets, such as :

The negatives are all the integers less than zero. And remember that an even number is defined as any integer multiple of two. Again there are many elements in common including :

The naturals are the counting numbers, while the wholes are all the naturals and zero. These two sets share many elements in common such as .

450 ends in a "0" and is therefore a multiple of both 2 and 5. Also, since

,

450 is a multiple of 3.

Therefore,

.

We are looking for an element of - that is, a multiple of 2, 3, and 5. All five choices are multiples of 5 (ending in a "5" or a "0"); 725 and 735 can be eliminated as they are not multiples of 2 (ending in a "5"). We test 720, 730, and 740 to find the multiple of 3:

720 is the correct choice.

In the above set, four of the numbers are all even .

The only one that is not even, also making it your answer, is since it is an odd number.