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Math Beast
Each week, we post a new GRE Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

If x and y are integers such that x < y and xy = 4, which of the following could be the value of 2x + 4y?

 

To see this week’s answer choices and to submit your pick, visit our Challenge Problem page.

Math Beast
Each week, we post a new GRE Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

If n is a positive integer greater than 1, then the function p(n) represents the product of all the prime numbers less than or equal to n. Which of the following is the second smallest prime factor of p(11) + 12?

 

To see this week’s answer choices and to submit your pick, visit our Challenge Problem page.

Math Beast
Each week, we post a new GRE Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

gre challenge

  • Quantity A is greater.
  • Quantity B is greater.
  • The two quantities are equal.
  • The relationship cannot be determined from the information given.

 

To see this week’s answer choices and to submit your pick, visit our Challenge Problem page.

We hope everyone had a happy Halloween! Yesterday we asked our friends on our Manhattan GRE Facebook page to attempt this Trick-or-Treat Halloween Challenge Problem. As promised, today we are sharing the answer and explanation to the problem:

Halloween

Let’s use x for the number of bags produced by the original recipe, and for the weight of each of the bags. Given those variables, our first equation is simply xy = 600. We also need to create an equation that represents the new recipe. Since the number of bags produced has increased by 30, and the weight of each bag has decreased by 1, the new equation is (x + 30)(y – 1) = 600. Remember, the total weight is still 600 ounces. Foiling this equation yields xy – x + 30y – 30 = 600.

We now have two equations with two variables. There are several different paths we can go down here, but all involve substitution of one of the variables, and all will yield a quadratic. The simplest path is to recognize that since xy = 600, we can substitute for xy in the second equation to get 600 – x + 30y – 30 = 600. Subtracting the 600 from both sides, and adding an x to each side gives us 30y – 30 = x. We can now substitute for x in the first equation.

wordbeast

 

 
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Math BeastEach week, we post a new GRE Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

If x is a positive integer and the first nonzero digit in the decimal expansion of  is in the hundredths place, what is the value of x?

 

Submit your pick over on our Challenge Problem page.