All GRE Subject Test: Math Resources
Example Questions
Example Question #1 : Probability & Statistics
A student has 14 piece of gum, 3 are spearmint, 5 are peppermint, and the rest are cinnamon. If one piece of gum is chosen at random, which of the following is NOT true.
The probability of picking a cinnamon or a peppermint is .
The probability of picking a cinnamon is .
The probability of picking a spearmint or a cinnamon is .
The probability of picking a spearmint is .
The probability of not picking a cinnamon is .
The probability of picking a spearmint or a cinnamon is .
The probability of picking a spearmint or a cinnamon is the addition of probability of picking a spearmint and the probability of picking a cinnamon
not
Example Question #1 : Sample Spaces
If I toss a coin 3 times, how many times will I roll at least one head?
None of the Above
Step 1: We need to find out how many outcomes there will be.
If we roll a coin three times, there are outcomes.
If we roll a coin times, there will be outcomes.
Step 2: Find all the outcomes.
The outcomes here are: HHH, HHT, HTH, HTT, THH, THT, TTH, and TTT.
Step 3: In the list of outcomes, count how many times the letter H appears at least once.
The letter "H" appears in HHH, HHT, HTH, HTT, THH, THT, and TTH.
The letter "H" appears in of the outcomes.
The probability of getting at least one H in the outcomes in Step 2 is .
Example Question #1 : Other Topics
How many different combinations can i have when flipping a coin three times?
Step 1: Let's answer a smaller problem. How many ways can I toss one coin?
There are two ways, either I get Heads or Tails.
Step 2: How about two coins?
There are four ways... They are, HH, HT, TH, and TT
Step 3: How many different combinations for three coins?
Let's List them:
HHH, HHT, HTH, THH, TTT, THT, TTH, HTT
There are different combinations.
Example Question #2 : Other Topics
Find the mean of the following set of numbers:
The mean can be found in the same way as the average of a group of numbers. To find the average, use the following formula:
So, if our set consists of
We will get our mean via:
So our answer is
Example Question #1 : Probability & Statistics
The mean of four numbers is .
A: The sum of the four numbers.
B:
Both are equal.
Quantity A is greater.
Quantity B is greater.
Can't be determined from the given information.
Both are equal.
To find the sum of the four numbers, just multiply four and the average. By multiplying the average and number of terms, we get the sum of the four numbers regardless of what those values could be.
Since Quantity A matches Quantity B, answer should be both are equal.
Example Question #1 : Statistics
Mean of is . are all positive integers. is between and inclusive.
A: Mean of .
B: Mean of .
Can't be determined from the information above.
Quantity B is greater.
Both are equal.
Quantity A is greater.
Can't be determined from the information above.
Let's look at a case where .
Let's have be and be . The sum of the three numbers have to be or .
The average of is or . The avergae of is or .
This makes Quantity B bigger, HOWEVER, what if we switched the and values.
The average of is still or . The avergae of is or .
This makes Quantity A bigger. Because we have two different scenarios, this makes the answer can't be determined based on the information above.
Example Question #3 : Other Topics
If and are positive integers from inclusive, then:
A: The mean of
B: The mean of
Quantity B is greater
Can't be determined from the information above
Quantity A is greater
Both are equal
Can't be determined from the information above
Let's add each expression from each respective quantity
Quantity A:
Quantity B:
Since we will let and . The sum of Quantity A is and the sum of Quantity B is also . HOWEVER, if was , that means the sum mof Quantity B is . With the same number of terms in both quantities, the larger sum means greater mean. First scenario, we would have same mean but the next scenario we have Quantity B with a greater mean. The answer is can't be determined from the information above.
Example Question #1 : Mean
John picks five numbers out of a set of seven and decides to find the average. The set has .
A: John averages the five numbers he picked from the set.
B:
Can't be determined from the information above
Quantity A is greater
Quantity B is greater
Both are equal
Quantity B is greater
To figure out which Quantity is greater, let's find the highest possible mean in Quantity A. We should pick the biggest numbers which are . The mean is . This is the highest possible mean and since Quantity B is this makes Quantity B is greater the correct answer.
Example Question #6 : Mean
Find the mean.
To find the mean, add the terms up and divide by the number of terms.
Example Question #1 : Other Topics
Find if the mean of is .
To find the mean, add the terms up and divide by the number of terms.
Then add the numerator.
Cross-multiply.
Subtract on both sides.