All GRE Subject Test: Math Resources
Example Questions
Example Question #12 : Combinational Analysis
Evaluate:
Step 1: Expand the numerator and denominator:
Step 2: Cross all numbers out that are common to both the numerator and denominator:
We are left with .
The value of
Example Question #61 : Other Topics
What is ?
Step 1: Recall definition of factorial...
Factorial is a mathematical expression where you multiply by every number below it until I hit . To find each number, subtract from the previous number
Step 2: Write out
Example Question #561 : Gre Subject Test: Math
Evaluate:
Step 1: Evaluate
Factorial-Multiply the number in front of the exclamation point by every number below until I hit
Example Question #562 : Gre Subject Test: Math
Evaluate:
Step 1: Evaluate each factorial expression separately...
Step 2: Take the evaluation of each expression and apply the operations in the problem:
So, we get
Example Question #563 : Gre Subject Test: Math
Evaluate:
Step 1: Apply the power rule (stacked) of exponents..
We get
Step 2: Evaluate the exponent...
We get
Step 3: Re-write the base:
Final answer:
Example Question #564 : Gre Subject Test: Math
Evaluate:
Step 1: Evaluate the parentheses first
Step 2: Multiply the outside by the final value in Step 1..
Example Question #565 : Gre Subject Test: Math
Evaluate:
Step 1: Define Factorial
Factorial is a mathematical expression which you multiply the number in front of the exclamation point by every number below it until you hit 1..
Step 2: Evaluate
Example Question #67 : Other Topics
Evaluate:
None of the other answers
Evaluate :
Evaluate :
Evaluate :
Example Question #17 : Factorials
Simplify the following expression:
Recall that ! means factorial in math. This means we multiply the number by all positive integers less than itself. In other words, this...
Becomes
This is a great job for a calculator, which yields:
Example Question #21 : Combinational Analysis
Mohammed is being treated to ice cream for his birthday, and he's allowed to build a three-scoop sundae from any of the thirty-one available flavors, with the only condition being that each of these flavors be unique. He's also allowed to pick different toppings of the available , although he's already decided well in advance that one of them is going to be peanut butter cup pieces.
Knowing these details, how many sundae combinations are available?
Because order is not important in this problem (i.e. chocolate chip, pecan, butterscotch is no different than pecan, butterscotch, chocolate chip), it is dealing with combinations rather than permutations.
The formula for a combination is given as:
where is the number of options and is the size of the combination.
For the ice cream choices, there are thirty-one options to build a three-scoop sundae. So, the number of ice cream combinations is given as:
Now, for the topping combinations, we are told there are ten options and that Mohammed is allowed to pick two items; however, we are also told that Mohammed has already chosen one, so this leaves nine options with one item being selected:
So there are 9 "combinations" (using the word a bit loosely) available for the toppings. This is perhaps intuitive, but it's worth doing the math.
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