GRE Math : Complex Fractions

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #1 : How To Find A Complex Fraction

Gre chart

For what year was there the greatest percent difference between the GDPs of Beetleton and Catterpilly?

Possible Answers:

Correct answer:

Explanation:

The simplest way to do this problem is visually. From looking at the graph, the greatest difference between Beetleton and Caterpilly is 2 billion US, and this difference is also observed where those points for Beetleton and Caterpilly are closest to the x-axis: 2008.

Of course, the percent differences can also be calculated using the formula:

and for each year, the percent differences are as follows:

Of course this method is much more time consuming.

Example Question #2 : How To Find A Complex Fraction

Gre chart

Caterpilly is projected to see the same percentage growth from 2014 to 2015 as was seen between 2010 and 2011. What is the approximate projected GDP for Caterpilly in 2015 in billions of US dollars to the nearest tenth?

Possible Answers:

Correct answer:

Explanation:

Percent growth is given by the formula:

So the percent grown for Caterpilly from 2010 to 2011 is:

Conversely, if percent growth is known, a new value can be found as follows:

The GDP for 2014 is  ( in billions US dollars), so the projected GDP in billions of US dollars for 2015 is:

Example Question #3 : How To Find A Complex Fraction

Megaton High is holding elections for the school president, vice president, and chief hall monitor, as well four secretarial positions which are identical.  If a total of  students are in the running for either president, vice president, or hall monitor,  students are in the running for the secretarial positions, and no student can hold more than one position, how many possible election results are possible?

Possible Answers:

Correct answer:

Explanation:

For this problem, note that for the  students elected from the  running for either president, vice president, and hall monitor, position matters, and so this is dealing with a permution, with the following number of potential outcomes:

However, for the second election, in which  students are competing for  positions, since all the secretarial offices are equal, position does not matter, and so we are dealing with a combination:

The total potential outcomes is given by the product of these two values:

Example Question #1 : How To Subtract Complex Fractions

Simplify the following:

Possible Answers:

Correct answer:

Explanation:

This problem merely requires careful working out of each part. Begin by simplifying the first fraction:

The numerator will be:

The denominator will be:

Thus, we have the following fraction:

Remember that you must multiply the numerator by the reciprocal of the denominator:

Now, work on the second fraction:

This fraction is much easier. After simplifying the numerator, you get:

This is the same as:

Thus, we come to our original expression! It is:

 

The common denominator of these fractions is . Thus, you have:

Example Question #2 : How To Subtract Complex Fractions

Quantity A: 

Quantity B: 

Possible Answers:

Quantity A is greater.

Quantity B is greater.

The two quantities are equal.

The relationship between A and B cannot be determined.

Correct answer:

Quantity A is greater.

Explanation:

As it is, quantities A and B have different denominators, so making a comparison can be tricky. Making a common denominator will allow for comparison of just the numerators, so that would make a good first step:

Quantity A:

Quantity B:

Disregarding equal denominators, since they'll always have a positive value, compare the numerators. If  is subtracted from quantity A and from quantity B, we're left with  for the former and  for the latter.

Quantity A is greater.

Example Question #2 : How To Subtract Complex Fractions

Quantity A: 

Quantity B: 

Possible Answers:

Quantity A and Quantity B are equal.

Quantity A is greater.

The relationship between A and B cannot be determined.

Quantity B is greater.

Correct answer:

The relationship between A and B cannot be determined.

Explanation:

One way to approach this question is to try to reduce the complexity of each quantity. By subtracting the value of Quantity A,  from both A and B, we can make a new comparison:

Quantity A': 

Quantity B': 

Now, it's easy to see that for different values of  Quantity B may be greater, lesser, or equal to Quantity A.

Since  is not restricted in its possible values, the relationship cannot be determined.

Example Question #3 : How To Subtract Complex Fractions

Rhoda can prune  rhododendrons in  hours, while Rhonda can prune  in  hours. If a work day is  hours, how many rhododendrons will Rita have to prune per hour so that the team prunes the garden's  rhododendrons?

Possible Answers:

Correct answer:

Explanation:

To find out how many rhododendrons Rita will need to prune in an hour, we must first find out how many she needs to prune.

If Rhoda can prune  rhododendrons in  hours, then she can prune  in  hours, and if Rhonda can prune  in  hours, she can prune  in  hours.

If this is not readily apparent, it can be found by finding out how many each prunes in one hour, then multiplying by .

Rhoda:

Rhonda: 

Between Rhoda and Rhonda,  of the  rhododendrons can be pruned, leaving  for Rita.

Since she has  hours for the task, her rate of pruning can be found to be:

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