Posts filed under 'GMAT Practice Questions'
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
Answer: E
Explanation:
In order to find the sum of consecutive numbers, we always follow three steps:
1. Find the number of numbers
2. Find the middle number
3. Multiply
Using the 3 steps -
1. Find the number of numbers:
The multiples of five between 23 and 92 are really the numbers starting from 25 and ending with 90. To find the number of numbers, subtract 25 from 90, divide by 5, and add 1:
90 – 25 = 65
65/5 = 13
13 + 1 = 14
2. Find the middle number:
The middle number between 25 and 90 is the average of 25 and 90:
25 + 90 = 115
115/2 = 57.5
3. Multiply:
57.5*14 = 805
September 24th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
What is the sum of the multiples of 5 between 23 and 92, inclusive?
A) 14
B) 65
C) 70
D) 747.5
E) 805
September 23rd, 2008
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
Answer: C
To be a perfect square, you must be able to take the square root of Q. Practically, that means both x and y need to be even numbers.
Statement 1: We learn that Q has at least 4 3’s and 2 7’s in its prime factors, but we don’t know there aren’t more than that. Q could have 5 3’s, which case y would be 5 and you would not be able to square root Q.
Statement 2: Since 243 is 35 and 343 is 73, Q has less than 5 3’s, and less than 3 7’s in its prime factors. But again, y could be any number less than 5 and x any number less than 3, even or odd.
Together – Q has exactly 4 3’s and 2 7’s in its prime factors and is therefore a square of an integer.
September 17th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
Q=3y7z. Is Q a square of an integer?
1) 81 and 49 are factors of Q.
2) 243 and 343 are NOT factors of Q.
September 16th, 2008
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
Answer: C
The average of the three numbers is 44, so they must add up to 132.
We know the median is 42, so the numbers, arranged in order, look like:
x, 42, y
We want the smallest number that the largest number can be, meaning, we want the smallest value of y.
To get the smallest value of y, we need x to be as large as it can be. 42 is the median, which means it’s in the middle, but it does not mean that the largest x can be is 41. x can be 42 as well. If that is the case, then 42 + 42 + y = 132, or y = 48.
September 10th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
The average of three positive integers is 44 and the median is 42. What is the least possible value of the greatest of the three numbers?
A) 6
B) 42
C) 48
D) 89
E) 128
September 9th, 2008
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
ANSWER: C
This is the only advanced algebra you’ll need on the test. It’s not the only way to solve it, but it’s the easiest way to solve it.
To find a maximum or minimum value of an equation with an exponent in it, you take the derivative of the equation, set it to zero, and solve. That’s the max or min.
In this case we are given
P = -25x2 + 7500x
To find the derivative, multiply each number by the exponent it’s connected to, and subtract the exponent by 1. Here, that will look like:
P’ = -50x + 7500
Set P’ to zero, and solve:
0 = -50x + 7500
50x = 7500
x = 150
If you’re not sure this really worked, try plugging in numbers, or even running the original equation in Excel. You will see that at x = 150, P is the maximum it can be.
July 30th, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
In a certain company, the formula for maximizing profits is P = -25x2 + 7500x, where P is profit and x is the number of machines the company operates in its factory. What value for x will maximize P?
A) 10
B) 50
C) 150
D) 200
E) 300
July 29th, 2008
Yesterday, we posted a 700+ level GMAT question. Below is the answer and explanation. How’d you do?
Answer: C
The sum of three integers is even – they can’t all be odd so the product will be even and B and D are eliminated.
To go further we must actually work.
Let’s make the mode be x. If it is a mode and there are three integers it must appear twice. Hence our three numbers are x-13 (the smallest), x and x.
x + x + (x – 13) = 50
3x – 13 = 50
x = 21
8*21*21 =
8*441 = 3,528
July 23rd, 2008
Every Tuesday we post a 700+ level GMAT question here on our blog, and post the answer and explanation the following day. Do you have what it takes?
The sum of 3 integers is 50. The smallest integer is 13 less than the mode. What is the product of the three integers?
A) 1,108
B) 2,041
C) 3,528
D) 4,111
E) 5,012
July 22nd, 2008
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