by Rich Cohen \u00a0Rich.C@empowergmat.com \u00a0www.EMPOWERgmat.com<\/p>\n
This series of emails and PMs focuses on situations that many Test Takers face during their studies. The names of the original posters have been changed to protect their identities.<\/p>\n
\u201cRe-writing\u201d DS Questions<\/strong> I was working through a practice DS question, but had trouble understanding part of the explanation. The question says:<\/p>\n \"If k is an integer greater than 1, and S is the sum of all positive divisors of k, is S>k+1?\"<\/p>\n The rephrase in the explanation was \"Is k not prime?\" Can you help explain what this means?<\/p>\n Jacques<\/p>\n Hi Jacques,<\/p>\n This DS question (like many DS questions) is based on a Number Property.<\/p>\n The term \"prime number\" refers to a positive integer that is divisible by just 2 things: itself and the number 1.<\/p>\n Here are some primes: 2, 3, 5, 7, 11\u2026.<\/p>\n Since most numbers are NOT prime, they have additional factors.<\/p>\n For example, the factors of 8 are 1, 2, 4 and 8<\/p>\n This means that when you sum up all the factors (divisors) of a number, you'd get a total that is GREATER than that number + 1. With prime numbers however, you would get a sum that was EQUAL to that number + 1.<\/p>\n In this question, if K = 8, then S = 1+2+4+8 = 15 and the answer to the question would be YES In effect, it's asking whether K is a prime number or not.<\/p>\n Comparison Rules in SC Questions<\/strong> Why is Answer A not correct here?<\/p>\n Like Austen, the characters of Forster are concerned largely with achieving economic security in a world riddled with class distinctions.<\/p>\n a) Like Austen, the characters of Forster Kellen<\/p>\n Hi Kellen,<\/p>\n This SC is based on Comparison rules, meaning that we have to compare LIKE things.<\/p>\n Here, we can compare Austen to Forster or we can compare Austen's characters to Forster's characters.<\/p>\n Answer A compares Austen to the characters of Forster, which is an invalid comparison.<\/p>\n With that insight, which answer would you choose?<\/p>\n Be THOROUGH When Dealing With DS Questions<\/strong> I\u2019ve attempted this DS question, but I get answer A and the correct answer is answer C. What am I missing here (sorry the question did not have an explanation with it)?<\/p>\n 1. How many integers x exist such that a < x < b? Lucille<\/p>\n Hi Lucille,<\/p>\n This DS question is built around a test of your thoroughness. Notice how you are NOT told anything about A and B\u2026.?<\/p>\n We're asked how many integers are between A and B. This is a perfect question for TESTing Values<\/p>\n Fact 1: B - A = 7<\/p>\n If B = 8 and A = 1, then the integers between them are 2, 3, 4, 5, 6, and 7 (a total of 6 integers) Fact 2: A and B are integers. Combined, we know that B - A = 7 AND A and B are integers. This means that there must be exactly 6 integers between them. You can TEST any set of values that fit these rules and you'll get the same answer every time. Final Answer: C<\/p>\n GMAT assassins aren't born, they're made, by Rich Cohen \u00a0Rich.C@empowergmat.com \u00a0www.EMPOWERgmat.com This series of emails and PMs focuses on situations that many Test Takers face during their studies. The names of the original posters have been…<\/p>\n","protected":false},"author":156,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,1,243,940],"tags":[],"class_list":["post-34788","post","type-post","status-publish","format-standard","hentry","category-gmat","category-uncategorized","category-blog","category-gmat-prep-gmat","entry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\n\t\t\n
\nHi Rich,<\/p>\n
\nIn this question, if K = 2, then S = 1+2 = 3 and the answer to the question would be NO.<\/p>\n
\nDear Rich,<\/p>\n
\nb) Like Austen, Forster's characters
\nc) Like Austen's, Forster's characters
\nd) As with Austen, Forster's characters
\ne) As are Austen's Forster's characters<\/p>\n
\nRich,<\/p>\n
\n(1) b - a = 7
\n(2) a and b are integers<\/p>\n
\nIf B = 8.5 and A = 1.5, then the integers between them are 2, 3, 4, 5, 6, 7 and 8 (a total of 7 integers)
\nFact 1 is INSUFFICIENT.<\/p>\n
\nSince we don't know what A and B are, there's really no way to answer this question\u2026..but if you're looking for proof\u2026.
\nIf B = 8 and A = 1, then the answer to the question is 6 integers
\nIf B = 2 and A = 1, then the answer to the question is 0 integers.
\nFact 2 is INSUFFICIENT<\/p>\n
\nCombined, SUFFICIENT.<\/p>\n
\nRich<\/p>\n","protected":false},"excerpt":{"rendered":"