GRE Subject Test: Math : Permutations

Study concepts, example questions & explanations for GRE Subject Test: Math

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Example Questions

Example Question #92 : Probability & Statistics

How many three-digit numbers can I create from the set of numbers ?

Possible Answers:

Correct answer:

Explanation:

Step 1: Identify if there are any restrictions to how the numbers can be made...

There are no restrictions, so we can have repeating numbers.

Step 2: Determine how many numbers can go in each slot..

First Slot: 7 choices
Second Slot: 7 Choices
Third Slot: 7 choices

Step 3: Multiply the choices for all three sets together:



We can create  different three-digit numbers...

Example Question #41 : Combinational Analysis

How many non-repetitive three-digit numbers can I create from the set of numbers ?

Possible Answers:

Correct answer:

Explanation:

Step 1: See if there are any restrictions..

We see we want only non-repetitive numbers...

Step 2: Find how many numbers can be put in each spot:

First Spot: 
Second Spot: 
Third Spot: 

Step 3: Multiply the number of choices of each spot



I can create  non-repetitive three-digit numbers...

Example Question #42 : Combinational Analysis

How many ways can I arrange the letters in the word ?

Possible Answers:

Correct answer:

Explanation:

Step 1: Count how many letters are in the word MISSISSIPPI...

There are 11 numbers.

Step 2: Find which letters repeat, and how many times it repeats:

 times
 times
 times

Step 3: Use formula for arranging letters:



Step 4: Expand:



Step 5: Simplify Step 4:



I can rearrange the letters in MISSISSIPPI  times...

Example Question #51 : Combinational Analysis

How many ways can I arrange the letters in the word CORRECT?

Possible Answers:

Correct answer:

Explanation:

Step 1: Count how many letters are in the word CORRECT...

There are  letters.

Step 2: Find any letters that repeat and how many times they repeat:

C (two times), R (two times)

Step 3: Find how many ways can I arrange the letters:

Example Question #52 : Combinational Analysis

 people are at a farewell party. At the end of the night, each person shakes hands. How many handshakes are made? 

NOTE: No two people can shake hands more than once.

Possible Answers:

Correct answer:

Explanation:

Step 1: Determine how many people are there..
There are  people.
Step 2: Determine how many people shake hands in a handshake...
 people make one handshake.
Step 3: Determine how many handshakes can be made...
We have a restriction here, so we need to use permutation..

So, there will be  handshakes.

 handshakes

Example Question #101 : Probability & Statistics

In how many ways can I rearrange the letters in the word "ANACONDA"?

Possible Answers:

Correct answer:

Explanation:

Step 1: Count how many letters are in the word ANACONDA...

There are 8 letters.

Step 2: Count how many repeats of any letters (if any)..

There are  A's and  N's.

Step 3: Find how many ways I can rearrange...

 

Example Question #101 : Probability & Statistics

How many ways can I arrange the letters in the word ?

Possible Answers:

Correct answer:

Explanation:

Step 1: Count how many numbers are in the word...

There are  letters. 

Step 2: Count the number of repeated letters...

There are  T's

There are  O's

There are  R's

Step 3: To find how many ways I can arrange the letters, take the factorial of the total number of letters and divide it by the factorial of how many times a certain letter repeats...

So, 

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