All GRE Math Resources
Example Questions
Example Question #81 : Algebra
Abby works at a car dealership and receives a commission "c" which is a percent of the profit the dealership makes from the sale, which is the difference between the price "p" of the car and the value "v" of the car. How much, in dollars, does the dealership earn per transaction?
(p – v)(1 – c)
(p – v)(1 – 0.01c)
pv(0.01c)
p(v – 0.01c)
(p – v)(0.01c)
(p – v)(1 – 0.01c)
To show that c is of the profit of the transaction, we must represent the profit as the difference between the price and the value of the car, or "(p – v)"
To show that Abby's commission in dollars is a percentage of the profit, we use 0.01 * c to convert the commission she earns to a percent.
To shift the earnings from Abby to the dealership (which is what the question requires of us), we must take 1 – 0.01c since this will accommodate for the remaining percentage. For example, it shifts 75% (0.75) to 25% (1 – 0.75 or 0.25).
Putting this all together, we get a final expression of:
(p – v)(1 – 0.01c) = dealership earnings
Check answer with arbitrary values: letting p = 300, v = 200, and c = 20, we get a value of 80 which makes sense as the $100 profit must be distributed evenly between Abby ($20) and the dealership ($80).
Example Question #11 : How To Find The Solution To An Equation
Sally is 2 years younger than Abby
Daisy is 5 years older than Tracy
Abby is 6 years older than Tracy
A
---
Sally's age
B
---
Daisy's age
Quantity B is greater
The two quantities are equal
The relationship cannot be determined
Quantity A is greater
Quantity B is greater
To simplify the word problem, express the ages in terms of variables in a system of equations. Note that we want to compare S with D:
S = A – 2
D = T + 5
A = T + 6
By substituting A for T in the first equation, we can get S in terms of T, which will let us directly compare the values of S and D.
S = (T + 6) – 2 = T + 4
If D = T + 5, and S = T + 4, D must be the greater value and Daisy is one year older than Sally. B is the correct answer.
Example Question #83 : Algebra
Quantitative Comparison
3x + 4y = 5
x – y = 6
Quantity A: x
Quantity B: y
Quantity A is greater.
The two quantities are equal.
The relationship cannot be determined from the information given.
Quantity B is greater.
Quantity A is greater.
First let's solve for y using the second equation, x – y = 6.
x = 6 + y. Then plug this in to the other equation.
3 (6 + y) + 4y = 5
18 + 3y + 4y = 5
18 + 7y = 5
7y = –13
y = –13/7. Now plug this value back into x = 6 + y.
x = 6 – 13/7 = 29/7. x is positive and y is negative, so clearly x is larger, so Quantity A is bigger.
Example Question #21 : How To Find The Solution To An Equation
x + y = 12 and 2x – y = 6
Quantity A: x
Quantity B: y
The relationship cannot be determined from the information given.
Quantity A is greater.
Quantity B is greater.
The two quantities are equal.
The two quantities are equal.
Because there are two different equations for the two variables (x and y), you are able to solve for the value of each. You can rearrange the first equation to show that
y = 12 – x by subtracting x from both sides.
Then you can substitute this equation into the second equation to give you
2x – (12 – x) = 6.
This new equation can be simplified to
2x – 12 + x = 6
3x =18
x = 6
Filling this back into the first equation, we get 6 + y = 12 which means y must also equal 6. Because x and y are equal, we choose the option both quantities are equal.
Example Question #21 : How To Find The Solution To An Equation
A theme park charges $10 for adults and $5 for kids. How many kids tickets were sold if a total of 548 tickets were sold for a total of $3750?
248
431
346
269
157
346
Let c = number of kids tickets sold. Then (548 – c) adult tickets were sold. The revenue from kids tickets is $5c, and the total revenue from adult tickets is $10(548 – c). Then,
5c + 10(548 – c) = 3750
5c + 5480 – 10c = 3750
5c = 1730
c = 346.
We can check to make sure that this number is correct:
$5 * 346 tickets + $10 * (548 – 346) tickets = $3750 total revenue
Example Question #71 : Algebra
Two palm trees grow next to each other in Luke's backyard. One of the trees gets sick, so Luke cuts off the top 3 feet. The other tree, however, is healthy and grows 2 feet. How tall are the two trees if the healthy tree is now 4 feet taller than the sick tree, and together they are 28 feet tall?
11 and 17 feet
12 and 16 feet
cannot be determined
14 and 14 feet
8 and 20 feet
12 and 16 feet
Let s stand for the sick tree and h for the healthy tree. The beginning information about cutting the sick tree and the healthy tree growing is actually not needed to solve this problem! We know that the healthy tree is 4 feet taller than the sick tree, so h = s + 4.
We also know that the two trees are 28 feet tall together, so s + h = 28. Now we can solve for the two tree heights.
Plug h = s + 4 into the second equation: (s + 4) + s = 28. Simplify and solve for h: 2s = 24 so s = 12. Then solve for h: h = s + 4 = 12 + 4 = 16.
Example Question #22 : How To Find The Solution To An Equation
Solve for z:
3(z + 4)3 – 7 = 17
–8
8
2
–2
4
–2
1. Add 7 to both sides
3(z + 4)3 – 7 + 7= 17 + 7
3(z + 4)3 = 24
2. Divide both sides by 3
(z + 4)3 = 8
3. Take the cube root of both sides
z + 4 = 2
4. Subtract 4 from both sides
z = –2
Example Question #72 : Algebra
Jen and Karen are travelling for the weekend. They both leave from Jen's house and meet at their destination 250 miles away. Jen drives 45mph the whole way. Karen drives 60mph but leaves a half hour after Jen. How long does it take for Karen to catch up with Jen?
She can't catch up.
For this type of problem, we use the formula:
When Karen catches up with Jen, their distances are equivalent. Thus,
We then make a variable for Jen's time, . Thus we know that Karen's time is (since we are working in hours).
Thus,
There's a logical shortcut you can use on "catching up" distance/rate problems. The difference between the faster (Karen at 60mph) and slower (Jen at 45mph) drivers is 15mph. Which means that every one hour, the faster driver, Karen, gains 15 miles on Jen. We know that Jen gets a 1/2 hour head start, which at 45mph means that she's 22.5 miles ahead when Karen gets started. So we can calculate the number of hours (H) of the 15mph of Karen's "catchup speed" (the difference between their speeds) it will take to make up the 22.5 mile gap:
15H = 22.5
So H = 1.5.
Example Question #24 : How To Find The Solution To An Equation
Bill and Bob are working to build toys. Bill can build toys in 6 hours. Bob can build toys in 3 hours. How long would it take Bob and Bill to build toys working together?
Bill builds toys an hour. Bob builds toys an hour. Together, their rate of building is . Together they can build toys in 2 hours. They would be able to build toys in 8 hours.
Example Question #25 : How To Find The Solution To An Equation
A hybrid car gets 40 miles per gallon. Gasoline costs $3.52 per gallon. What is the cost of the gasoline needed for the car to travel 120 miles?
The car will be using of gas during this trip. Thus, the total cost would be .