All GRE Subject Test: Math Resources
Example Questions
Example Question #1 : Combinational Analysis
Evaluate:
Step 1: We need to define factorial (!). The operation (!) means that you multiply the number next to the ! by the next consecutive number down to 1.
Step 2: Expand the equation:
Step 3: Evaluate the expression:
The answer to the expression is .
Example Question #2 : Factorials
is the product of consecutive numbers 1 through
Example Question #3 : Factorials
is the product of consecutive numbers 1 through
Example Question #51 : Other Topics
Evaluate:
Step 1: Rewrite the equation by using rule of factorials...
Rule of factorials: Multiply the number in front of factorial and each number one lower than the rest until I hit .
Step 2: Reduce any common numbers (colored in blue):
We get !
Step 3: Evaluate what's left
The value of the fraction is .
Example Question #52 : Other Topics
What is equal to?
depicts the permutation of n total objects with k objects being arranged.
Thus,
The upper factorial is the upper index, and the lower factorial is the difference of the indices.
The or will cancel out.
Example Question #3 : Combinational Analysis
Twelve horses run a race. In how many ways can 3 horses finish in 1st, 2nd, and 3rd place, in any order?
This particular question is asking one to find the combination. This is because the order of the 1st, 2nd, and 3rd place finishers is not important.
Thus evaluate .
Because and both consist of , the will cancel out leaving:
Example Question #1 : Combinational Analysis
Evaluate:
Step 1: Evaluate
Step 2: Evaluate
Step 3: Evaluate
Step 4: Evaluate
Step 5: Add/Subtract values:
Example Question #4 : Combinational Analysis
Evaluate:
Step 1: Do the division of the factorials
Step 2: Simplify by cancelling out any terms on both top and bottom:
Step 3: Multiply the result of the division by 3..
The value of that expression is .
Example Question #10 : Factorials
Evaluate:
Step 1: Find
Step 2: Find
Step 3: Subtract the values from step 1 and step 2:
The answer is
Example Question #51 : Other Topics
Evaluate:
Step 1: Write in multiplication form:
Step 2: Multiply Out