All GRE Math Resources
Example Questions
Example Question #1 : Simplifying Fractions
For how many integers, , between 26 and 36 is it true that
and are all in lowest terms?
If is even, then is not in lowest terms, since both and 4 are divisible by 2. Therefore, the only possibilities are 27,29,31,33, and 35. But , , and , so only two integers satisfy the given condition: 29 and 31.
Example Question #2 : Simplifying Fractions
Mrs. Lawrence's class has students, of which are girls. If you were to choose a student at random, what's the probability that the student chosen would be a boy?
In order to find out the probability of choosing a boy, you must first find out how many boys there are. Since there are girls out of students, students should be boys.
Therefore, the probability of choosing a boy is,
.
However, this is not one of the answer choices; therefore, you must reduce the fraction.
In order to reduce a fraction, you have to find their GCM, or greatest common multiple. This is the biggest number that will go into both the numerator and denominator . The largest number is . Divide both the top and bottom by , and you will get the answer:
Example Question #3 : Simplifying Fractions
Simplify the fraction:
To simplify the fraction
It may be helpful to write it in terms of scientific notation:
Example Question #2 : Simplifying Fractions
Simply the fraction:
To simplify the fraction
Begin by factoring out common terms in the numerator and denominator:
Now notice that the coefficients for the polynomials in the numerator and denominator match the form of Pascal's Triangle:
The fraction can be rewritten as:
And finally reduced to