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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 ## The youngest of 4 children has siblings who are 3, 5, and 8 ##### This topic has 3 expert replies and 0 member replies ### Top Member ## The youngest of 4 children has siblings who are 3, 5, and 8 ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling? A. 17 B. 18 C. 19 D. 21 E. 22 ### GMAT/MBA Expert GMAT Instructor Joined 09 Apr 2015 Posted: 1461 messages Followed by: 18 members Upvotes: 39 Top Reply BTGmoderatorDC wrote: The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling? A. 17 B. 18 C. 19 D. 21 E. 22 We can let x = the age of the youngest child; thus, the ages of the three older children are x + 3, x + 5 and x + 8, respectively. We can create the equation: (x + x + 3 + x + 5 + x + 8)/4 = 21 4x + 16 = 84 4x = 68 x = 17 Answer: A _________________ Jeffrey Miller Head of GMAT Instruction ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10112 messages Followed by: 494 members Upvotes: 2867 GMAT Score: 800 Top Reply Hi All, We're told that the YOUNGEST of 4 children has siblings who are 3, 5, and 8 years OLDER than she is and that the average age of the 4 siblings is 21. We're asked for the age of the youngest sibling. This question can be solved by TESTing THE ANSWERS. Since the average age is 21 and we're trying to figure out the age of the YOUNGEST sibling, we should look for an answer that is several years LESS than 21... Let's TEST Answer B: 18 years IF... Youngest = 18 Siblings = 21, 23 and 26 Sum = 88 Average = 88/4 = 22 This is TOO HIGH (the average is supposed to be 21). Since the average is too high, all 4 of the children are TOO OLD. There's only one answer left that would lower the average... Final Answer: A GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1821 messages Followed by: 29 members Upvotes: 470 BTGmoderatorDC wrote: The youngest of 4 children has siblings who are 3, 5, and 8 years older than she is. If the average (arithmetic mean) age of the 4 siblings is 21, what is the age of the youngest sibling? A. 17 B. 18 C. 19 D. 21 E. 22 Say the age of the youngest of 4 children is x, thus, the ages of the other three children are (x+3), (x+5) and (x+8), respectively. The sum of ages of the four children = x + (x+3) + (x+5) + (x+8) = 4x + 16 Average = (4x + 16)/4 = 21 => x + 4 = 21 => x = 17 The correct answer: A Hope this helps! -Jay _________________ Manhattan Review Test Prep Locations: Manhattan Review Himayatnagar | Free GMAT Practice Test | GRE Prep Jayanagar | Madhapur GRE Coaching | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. • Award-winning private GMAT tutoring Register now and save up to$200

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