2012 | Page 17 of 18

Disguising – and Decoding – Quant Problems

by Stacey Koprince Feb 23, 2012

How can the GMAT disguise a prime number (or any other) problem? That’s exactly what we’re going to discuss today! We’re going to use the concept of prime to describe this, but the general process of disguising “ and studying how to decode “ problems is applicable to a great number of problems on the test. Pay particular attention to the end of the article; you can use these concepts when studying a number of different GMAT content areas. Read more

Challenge Problem Showdown – February 21st, 2012

by mmapplebeck Feb 23, 2012

We invite you to test your GMAT knowledge for a chance to win! Each week, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for a free Manhattan GMAT Prep item. Tell your friends to get out their scrap paper and start solving!

Two integers between 1 and 100, inclusive, each randomly and independently chosen, are either added or multiplied, with an equal chance of either operation. What is the probability that the result is even?

Tackling a GMATPrep Critical Reasoning Weaken Problem

by Stacey Koprince Feb 21, 2012

This week, we’re going to discuss one of the most common critical reasoning problem types: Weaken the Conclusion. If you haven’t yet, read this article before we try our GMATPrep problem. Then set your timer for 2 minutes and go!

* Tiger sharks are common in the waters surrounding Tenare Island. Usually tiger sharks feed on smaller sharks, but sometimes they have attacked tourists swimming and surfing at Tenare’s beaches. This has hurt Tenare’s tourism industry, which is second only to its fishing industry in annual revenues. In order to help the economy, therefore, the mayor of the island has proposed an ongoing program to kill any tiger sharks within a mile of the beaches.

Which of the following, if true, most strongly calls into question the likelihood that implementation of the mayor’s proposal will have the desired consequences?
Read more

Challenge Problem Showdown – February 13th, 2012

by Tom Williams Feb 14, 2012

Standing on the origin of an xy-coordinate plane, John takes a 1-unit step at random in one of the following 4 directions: up, down, left, or right. If he takes 3 more steps under the same random conditions, what is the probability that he winds up at the origin again?

Inequalities

by Stacey Koprince Feb 13, 2012

Today we’ve got an inequalities data sufficiency question on tap from GMATPrep. Set your timer for 2 minutes and go!

Is m + z > 0?

(1) m “ 3z > 0
(2) 4z “ m > 0

This is a yes/no data sufficiency question. I’m just going to remind myself of the rules: an always yes answer to a statement is sufficient, an always no answer is also sufficient, and a maybe or sometimes yes / sometimes no answer is not sufficient.
Read more

Challenge Problem Showdown – February 6th, 2012

by Tom Williams Feb 7, 2012

Each of three investments has a 20% of becoming worthless within a year of purchase, independently of what happens to the other two investments. If Simone invests an equal sum in each of these three investments on January 1, the approximate chance that by the end of the year, she loses no more than 1/3 of her original investment is

More Modifiers and Meaning: a GMATPrep Sentence Correction Problem

by Stacey Koprince Feb 6, 2012

We’ve been examining the issues of modifiers and meaning quite a bit lately because these topics are both so important on the GMAT. I’ve got another one for you today.This problem is from GMATPrep. Set your timer for 1 minute 15 seconds and go for it!

* “Recently documented examples of neurogenesis, the production of new brain cells, include the brain growing in mice when placed in a stimulating environment or neurons increasing in canaries that learn new songs.
Read more

Challenge Problem Showdown – January 30th, 2012

by Tom Williams Jan 31, 2012

For all positive integers n and m, the function A(n) equals the following product:

(1 + 1/2 + 1/2²)(1 + 1/3 + 1/3²)(1 + 1/5 + 1/5²)…(1 + 1/p_n + 1/p_n²), where p_n is the nth smallest prime number, while B(m) equals the sum of the reciprocals of all the positive integers from 1 through m, inclusive. The largest reciprocal of an integer in the sum that B(25) represents that is NOT present in the distributed expansion of A(5) is

Challenge Problem Showdown – January 23rd, 2012

by Tom Williams Jan 31, 2012

The country of Sinistrograde uses standard digits but writes its numbers from right to left, so that place values are reversed. For instance, 12 means twenty-one. A five-digit code from Sinistrograde is accidentally interpreted from left to right. If all possible five-digit codes (including zeroes in all positions) are equally likely, what is the probability that the code is in fact interpreted correctly?

Statistical “Combo” Problems

by Stacey Koprince Jan 23, 2012

Today we’re going to talk about statistics problems in which we have to combine knowledge of more than oneconcept.Try this GMATPrep problem first; set your timer for 2 minutes and go!

Last month 15 homes were sold in Town X. The average (arithmetic mean) sale price of the homes was $150,000 and the median sale price was $130,000. Which of the following statements must be true?

I. At least one of the homes was sold for more than $165,000.

II. At least one of the homes was sold for more than 130,000 and less than 150,000.

III. At least one of the homes was sold for less than $130,000.

(A) I only

(B) II only

(C) III only

(D) I and II

(E) I and III

Sigh. I hate roman numeral questions. I have to do more work to solve the problem, and I never like that. : )

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Articles published in 2012