GRE Math : Arithmetic

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #481 : Arithmetic

 and  are positive integers.

 is a multiple of .

Quantity A:

Quantity B:

 

Possible Answers:

The two quantities are equal.

Quantity B is greater.

The relationship cannot be determined.

Quantity A is greater.

Correct answer:

The relationship cannot be determined.

Explanation:

Recall that the exponent of the denominator is sutracted from the exponent of the numerator. 

Therefore Quantity A is equivalent to x5–y, and because we would then be comparing an arithmetic operation to a geometric operation, it does not matter whether y is a multiple of 5.  The two quantities cannot be compared.

Example Question #1 : Mixed / Improper Fractions

Which of the following is the mixed fraction equivalent to ?

Possible Answers:

Correct answer:

Explanation:

To begin, notice that using your calculator, you can find:

Now, the closest even multiple of  that is less than  is .  Therefore, you know that your number is:

This is the same as:

, or simply, .  This is your mixed fraction.

Example Question #2 : Mixed / Improper Fractions

Which of the following is equivalent to ?

Possible Answers:

Correct answer:

Explanation:

Although there are many ways to convert improper fractions into mixed fractions, the easiest way is to use your calculator to your advantage.  Begin by dividing  by .  This gives you . Therefore, you can eliminate all the options that have do not have  for their first portion. Next, multiply  by the denominator (), and get .  This means that you have  and , or .  Thus, your answer is .

Example Question #483 : Arithmetic

Quantity A: 

Quantity B: 

Which of the following is true?

Possible Answers:

Quantity B is larger.

Quantity A is larger.

The two quantities are equal

The relationship of the two quantities cannot be determined based on the information provided.

Correct answer:

The two quantities are equal

Explanation:

Though there are several ways you could solve this, let's convert the improper fraction into a mixed one so we can compare them. Start by dividing  by .  This gives you  

Now, since we know that the two numbers have the same whole-number value, we need to compare their decimal portions. Compare  to . The latter is indeed   Therefore, the two values are equal.

Example Question #2 : Mixed / Improper Fractions

Write as an improper fraction.

 

Possible Answers:

Correct answer:

Explanation:

To find the improper fraction value, we must effectively add together 71 and 5/7. To do this, we will give 71 a denominator of 7; therefore, we are transforming 71/1 to x/7.  The shortest way to do this is to multiply by 7/7 (which really is 1); therefore, 71 = 71 * (7/7) = 497/7.

Now add them: (497 + 5)/7 = 502/7

Example Question #71 : Fractions

Which of the following improper fractions is equivalent to ?

Possible Answers:

Correct answer:

Explanation:

To find an improper fraction, you need to multiply the whole number that you have by the denominator of the associated fraction.  For our problem, this means that you will multiply  by , getting .  Next, you add this to the numerator of your fraction, giving you , or .  Finally, you place this over your original denominator, giving you: 

Example Question #3 : Mixed / Improper Fractions

Which of the following improper fractions is equivalent to ?

Possible Answers:

Correct answer:

Explanation:

To find an improper fraction, you need to multiply the whole number that you have by the denominator of the associated fraction.  For our problem, this means that you will multiply  by , getting .  Next, you add this to the numerator of your fraction, giving you , or .  Finally, you place this over your original denominator, giving you: 

Example Question #1 : How To Find The Amount Of Rational Numbers Between Two Numbers

In terms of , what is the arithmetic mean of , and ?

Possible Answers:

Correct answer:

Explanation:

The arithmetic mean of a set is defined as the sum of terms in the set divided by the number of terms of a set. Therefore, the mean for this problem can be found as:

Example Question #485 : Arithmetic

Harold is drawing numbered slips of paper from a hat that are labeled  through .  What is the probability that he'll draw three numbers in a row that are divisible by three, given that a slip is not replaced after it is drawn?

Possible Answers:

Correct answer:

Explanation:

There are  slips of paper that have a number divisible by , which are 

The probability of one being drawn is . Once that slip is drawn, the probability of drawing a number divisible by  becomes , and on the third draw it is .

For this sequence of events to happen, the probability is the product of the three separate probabilities:

Example Question #484 : Arithmetic

Happy Harold's Creamery offers specials during the week on particular sundaes. Monday they offer the Triple Trouble, in which three different scoops may be chosen from the full thirty-one that HHC offers. Tuesday features, for the same price, the Fearsome Four, which is a sundae of four scoops; however, only twenty-one flavors may be chosen from.

Quantity A: The amount of sundae options available for the Triple Trouble.

Quantity B: The amount of sundae options available for the Fearsome Four.

Possible Answers:

The relationship between the two cannot be determined.

Quantity B is greater.

Quantity A is greater.

The two quantities are equal.

Correct answer:

Quantity B is greater.

Explanation:

Both of these sundae options are dealing with combinations, i.e. the order the scoops are chosen does not matter, and so the amount of possible combos is given by the formula:

Where  is the total number of options and  is the size of the combination created.

For the Triple Trouble, the total amount of possible sundaes is:

And for the Fearsome Four:

 

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