All GRE Math Resources
Example Questions
Example Question #41 : Proportion / Ratio / Rate
Carol ate 3 pancakes in 5 minutes. If she continues to eat at the same rate, how many whole pancakes can she eat in 24 minutes?
If Carol ate 3 pancakes in 5 minutes, she can eat of a pancake every minute. .
That means she ate 14 whole pancakes (and an additional 2/5 of another pancake).
Example Question #1123 : Gre Quantitative Reasoning
If 24 machines can make 5 devices in 30 minutes, how many hours will it take 4 machines to make 15 devices?
9 hours
5 hours
12 hours
3 hours
6 hours
9 hours
Approach this problem with the following reasoning.
Unit of work done = number of workers * rate * time
In our case, we are given 24 "workers," able to make 5 "units of work," in 0.5 "time." The rate is not given, but can be solved for with our given information.
Units of work = 5
Number of workers = 24
Time = 0.5 hours (30 minutes)
Now, since we know the rate, which does not chage, we can solve for the new time when the number of machines is decreased and the number of devices is increased.
Unit of work done = number of workers * rate * time
Example Question #1131 : Gre Quantitative Reasoning
Mario can solve problems in hours. At this rate, how many problems can he solve in hours?
The rate is given by amount of probems over time.
To find the amount of problems done in a given amount of time, mulitply the rate by the given amount of time.
We can combine our y terms and cancel our n terms to simplify.
Example Question #1132 : Gre Quantitative Reasoning
It takes Mary 45 minutes to completely frost 100 cupcakes, and it takes Benjamin 80 minutes to completely frost 110 cupcakes. How many cupcakes can they completely frost, working together, in 1 hour?
In this rate word problem, we need to find the rates at which Mary and Bejamin frost their respective cupcakes, and then sum their respective rates per hour. In one hour Mary frosts 133 cupcakes. (Note: the question specifies COMPLETELY frosted cupcakes only, so the fractional results here will need to be rounded down to the nearest integer.) Benjamin frosts 82 cupcakes.
82 + 133=215
Example Question #548 : Arithmetic
If John can paint a house in hours and Jill can paint a house in hours, how long will it take for both John and Jill to paint a house together?
This problem states that John can paint a house in hours. That means in hour he will be able to paint of a house.
The problem also states that Jill can paint a house in hours. This means that in hour, Jill can paint of a house.
If they are painting together, you simply add the rate at which the paint separately together to find the rate at which they paint together. This means in hour, they can paint of a house. Now to find the time that paint an entire house, we simply invert that fraction, meaning that to paint an entire house together it would take them of an hour, or .
The general formula for solving these work problems is , where is the amount of time it takes worker A to finish the job alone and is the amount of time it would take worker B to finish the job alone.
Example Question #1133 : Gre Quantitative Reasoning
Half of a salad is lettuce. A third of it is tomatoes. The remainder is made of cucumbers. Which of the following is the ratio of lettuce to cucumbers in the salad?
First, you need to compute the amount of cucumbers used for the salad. A whole salad can be represented as (like ). Thus, you know:
First, simplify the part of the equation to the left of the equals sign:
Thus, the ratio of lettuce to cucumbers is:
This can be simplified by multiplying both sides by :
Example Question #2 : How To Find The Ratio Of A Fraction
One third of a diet bar is made of shredded fiber. Of the remaining portion, a third is made of apples and the remainder is made of soy. What is the ratio of shredded fiber to soy?
We know that the bar could be represented as:
, where represents . Now, we know that . The remaining apples and soy comprise of the bar. Now, the apples are one third of that remaining . (This is italicized because it is very important. The common error will be to think that it they are one third of the whole bar.) So, we know apples then are:
Thus, we can compute the soy by subtracting that from the :
Now the ratio of fiber to soy is:
Multiply both factors by to simplify:
Example Question #3 : How To Find The Ratio Of A Fraction
A pie is made up of crust, apples, and sugar, and the rest is jelly. What is the ratio of crust to jelly?
A pie is made up of crust, apples, sugar, and the rest is jelly. What is the ratio of crust to jelly?
To compute this ratio, you must first ascertain how much of the pie is jelly. This is:
Begin by using the common denominator :
So, the ratio of crust to jelly is:
This can be written as the fraction:
, or
Example Question #1132 : Gre Quantitative Reasoning
In a solution, of the fluid is water, is wine, and is lemon juice. What is the ratio of lemon juice to water?
This problem is really an easy fraction division. You should first divide the lemon juice amount by the water amount:
Remember, to divide fractions, you multiply by the reciprocal:
This is the same as saying:
Example Question #1133 : Gre Quantitative Reasoning
If and , what is the ratio of to ?
To find a ratio like this, you simply need to make the fraction that represents the division of the two values by each other. Therefore, we have:
Recall that division of fractions requires you to multiply by the reciprocal:
,
which is the same as:
This is the same as the ratio: