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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote On the number line shown, the distance between 0 and a, a tagged by: BTGmoderatorLU This topic has 3 expert replies and 0 member replies Top Member On the number line shown, the distance between 0 and a, a Timer 00:00 Your Answer A B C D E Global Stats Difficult Source: e-GMAT In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. If the distance of point b from 15 is twice the distance of point a from 15, what is the value of |c|? A. 9 B. 27 C. 36 D. 45 E. 54 The OA is C. GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1952 messages Followed by: 30 members Upvotes: 470 BTGmoderatorLU wrote: Source: e-GMAT In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. If the distance of point b from 15 is twice the distance of point a from 15, what is the value of |c|? A. 9 B. 27 C. 36 D. 45 E. 54 The OA is C. We see that b > a. Given that the distance of point b from 15 is twice the distance of point a from 15, we can deduce that 15 must lie of the left of b. If were at the right of b, the condition "the distance of point b from 15 is twice the distance of point a from 15," cannot be met. Given that the distance between 0 and a, a and b, and a and c is in the ratio of 1 : 2 : 3, let's assume that the coordinate of a = x; thus, ab = 2x, and the coordinate of b = 3x and that of c is 4x. There are two scenarios: Scenario 1: 15 lies between 0 and a. Thus, b - 15 = 2(a - 15) b - 15 = 2a - 30 2a - b = 15 => 2x - 3x = 15 x = -15 Not possible since a = x and the coordinate of a is positive. Scenario 2: 15 lies between a and b. Thus, b - 15 = 2(15 - a ) b - 15 = 30 - 2a 2a + b = 45 => 2x + 3x = 45 x = 9 (possible) Thus, the coordinate of c = 4x = 4*9 = 36 The correct answer: C Hope this helps! I think there was no need to ask for the absolute value of c. Given c is on the right of 0 on the number line, it is positive. -Jay _________________ Manhattan Review GRE Prep Locations: GRE Classes Manhattan | GRE Prep Course Frankfurt | GRE Prep Bellevue | SAT Prep Course Orlando | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 BTGmoderatorLU wrote: Source: e-GMAT In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. If the distance of point b from 15 is twice the distance of point a from 15, what is the value of |c|? A. 9 B. 27 C. 36 D. 45 E. 54 Using info given (figure included) we have DATA and FOCUS as below: $0 < a < b < c\,\,\left( * \right)$ ${\text{dist}}\left( {0,a} \right) = a$ $\left. \begin{gathered} {\text{dist}}\left( {a,b} \right) = 2a\, \hfill \\ {\text{dist}}\left( {a,c} \right) = 3a \hfill \\ \end{gathered} \right\}\,\,\,\mathop \Rightarrow \limits^{\left( * \right)} \,\,\,{\text{dist}}\left( {b,c} \right) = 3a - 2a = a$ $? = c = {\text{dist}}\left( {0,c} \right) = 4a$ From the fact that ${\text{dist}}\left( {b,15} \right) = 2 \cdot {\text{dist}}\left( {a,15} \right)\,\,\,\,\,$ We have three possibilities: $b < 15:\,$ $15 - b = 2\left( {15 - a} \right)\,\,\,\, \Rightarrow \,\,\,\,15 = 2a - b = 2a - 3a = - a\,\,\,\, \Rightarrow \,\,\,a < 0\,\,\,\,{\text{impossible}}\,\,$ $a < 15 \leqslant b:$ $b - 15 = 2\left( {15 - a} \right)\,\,\,\, \Rightarrow \,\,\,\,3 \cdot 15 = 2a + b = 2a + 3a = 5a\,\,\,\, \Rightarrow \,\,? = 4a = 4 \cdot 9 = 36$ From the fact that we have already found (one viable) correct alternative choice, no need to evaluate the third scenario! This solution follows the notations and rationale taught in the GMATH method. Regards, Fabio. _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15313 messages Followed by: 1863 members Upvotes: 13060 GMAT Score: 790 BTGmoderatorLU wrote: Source: e-GMAT In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. If the distance of point b from 15 is twice the distance of point a from 15, what is the value of |c|? A. 9 B. 27 C. 36 D. 45 E. 54 In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. To determine the ratio of a to b to c, TEST AN EASY CASE. Let a=1. Since a is ONE PLACE to the right of 0, b must be TWO PLACES to the right of a (implying that b=3), while c must be THREE PLACES to the right of a (implying that c=4). Thus: a:b:c = 1:3:4. We can PLUG IN THE ANSWERS, which represent the value of c. When the correct answer is plugged in, the distance between b and 15 will be twice the distance between a and 15. The ratio above implies that the value of c will almost certainly be a MULTIPLE OF 4. Of the five answer choices, only C is a multiple of 4. C: 36 Since c=36 and a:b:c = 1:3:4 = 9:27:36, a=9 and b=27. Distance between b and 15 = 27-15 = 12. Distance between a and 15 = 15-9 = 6. Success! The distance between b and 15 is twice the distance between a and 15. The correct answer is C. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. 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