GRE Math : How to find the missing number in a set
Study concepts, example questions & explanations for GRE Math
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Example Questions
Example Question #1 : Sets
The product of two integers is 14. Which of the following could be the average of the two numbers?
The two integers in this case, and their respective averages, could be:
Only 
Example Question #2 : Sets
Which of these is a natural number?
All of these are natural numbers.
None of these are natural numbers .
The natural numbers are the positive integers (whole numbers) starting with 1.
Example Question #3 : Sets
Which of the following pairs of events are mutually exclusive?
the numbers less than 
the even numbers, the numbers greater than
the negative numbers,
the positive numbers, the numbers less than
the positive numbers, the numbers less than
We can think of mutually exclusive in terms of a Venn diagram. We are looking for the pair of events that has nothing in common. The only sets that don't have a single number in common are the positive numbers and the numbers less than –200.
Example Question #4 : Sets
In the set of positive, distinct integers 
We know that all the numbers are positive, so they are greater than zero. We also know that the numbers are distinct, so they are all unique.
We can write this as {a + b + 8 + d + e}, so let a and b be 1 and 2 respectively, the smallest possible positive, distinct integers. Then let d and e be 9 and 10, the smallest positive, distinct integers larger than 8.
We add the set {1 + 2 + 8 + 9 + 10} to find it equals 30.
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