• NEW! FREE Beat The GMAT Quizzes
Hundreds of Questions Highly Detailed Reporting Expert Explanations
• 7 CATs FREE!
If you earn 100 Forum Points

Engage in the Beat The GMAT forums to earn
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 ## A farmer constructs a fence along the northern edg tagged by: Brent@GMATPrepNow ##### This topic has 3 expert replies and 1 member reply ## A farmer constructs a fence along the northern edg A farmer constructs a fence along the northern edge of his property, using materials such that he places a post every 7 meters. if he uses 100 posts, how many meters will the fence span? a)686 b)693 c)700 d)707 e)770 Please assist with above problem. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12822 messages Followed by: 1247 members Upvotes: 5254 GMAT Score: 770 alanforde800Maximus wrote: A farmer constructs a fence along the northern edge of his property, using materials such that he places a post every 7 meters. if he uses 100 posts, how many meters will the fence span? a)686 b)693 c)700 d)707 e)770 Please assist with above problem. Let's look for a pattern... 1 post: fence span = 0 meters 2 posts: fence span = 7 meters 3 posts: fence span = 7 + 7 = 14 meters 4 posts: fence span = 7 + 7 + 7 = 21 meters 5 posts: fence span = 7 + 7 + 7 + 7 = 28 meters . . . We can see that, for n posts, we add 7 n-1 times . . . 100 posts: fence span = sum of 99 sevens = (99)(7) = 693 meters Answer: B RELATED VIDEO - Growth tables: https://www.gmatprepnow.com/module/gmat-word-problems/video/929 _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10124 messages Followed by: 494 members Upvotes: 2867 GMAT Score: 800 Hi alanforde800Maximus, This is an example of a 'fence post' problem (literally and figuratively). The 'key' to these types of questions is to remember that there's a 'first post' that you have to include in your total. Here's a much simpler example of this type of math - if you read pages 2 through 5 (inclusive) of a book, then how many pages did you read? It's 4 pages (not 3), since you read pages 2, 3, 4 and 5. Thus, we have the first post, then another post every 7 meters. That means that we're 99(7) meters away from the first post once we plant the last post. (99)(7) = 693 Final Answer: B GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com Senior | Next Rank: 100 Posts Joined 11 Aug 2012 Posted: 31 messages Brent@GMATPrepNow wrote: alanforde800Maximus wrote: A farmer constructs a fence along the northern edge of his property, using materials such that he places a post every 7 meters. if he uses 100 posts, how many meters will the fence span? a)686 b)693 c)700 d)707 e)770 Please assist with above problem. Let's look for a pattern... 1 post: fence span = 0 meters 2 posts: fence span = 7 meters 3 posts: fence span = 7 + 7 = 14 meters 4 posts: fence span = 7 + 7 + 7 = 21 meters 5 posts: fence span = 7 + 7 + 7 + 7 = 28 meters . . . We can see that, for n posts, we add 7 n-1 times . . . 100 posts: fence span = sum of 99 sevens = (99)(7) = 693 meters Answer: B RELATED VIDEO - Growth tables: https://www.gmatprepnow.com/module/gmat-word-problems/video/929 Thank you. I'm working on a similar problem. I'm trying to uncover the pattern involved. A farmer plans to build a fence next to a stretch of driveway. Each post will be one foot wide and there will be three feet of space between each post. If the driveway is 65 feet long and the fence will be on only one side of the driveway, how many posts will the farmer need to complete the fence? A.16 B.17 C.18 D.19 E.20 The pattern I'm seeing is: (#) posts + 3x feet = # of feet (1) post + 3(0) = 1 feet (2) posts + 3(1) = 5 feet (3) posts + 3(2) = 9 feet (4) posts + 3(3) = 13 feet . . . . (17) posts + 3(16) = 65 feet Is there another pattern that I'm not seeing in this problem? I understand the quick way to get the answer is 65/4, but I want to make sure I understand the pattern. Thanks so much. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12822 messages Followed by: 1247 members Upvotes: 5254 GMAT Score: 770 Poisson wrote: Thank you. I'm working on a similar problem. I'm trying to uncover the pattern involved. A farmer plans to build a fence next to a stretch of driveway. Each post will be one foot wide and there will be three feet of space between each post. If the driveway is 65 feet long and the fence will be on only one side of the driveway, how many posts will the farmer need to complete the fence? A.16 B.17 C.18 D.19 E.20 The pattern I'm seeing is: (#) posts + 3x feet = # of feet (1) post + 3(0) = 1 feet (2) posts + 3(1) = 5 feet (3) posts + 3(2) = 9 feet (4) posts + 3(3) = 13 feet . . . . (17) posts + 3(16) = 65 feet Is there another pattern that I'm not seeing in this problem? I understand the quick way to get the answer is 65/4, but I want to make sure I understand the pattern. Thanks so much. Looks good to me. So, algebraically speaking, if n = # of posts, then the length of the fence (including posts) = n + 3(n-1) = n + 3n - 3 = 4n - 3 So, for a 65-foot fence, we set the equation to 65.... 4n - 3 = 65 Solve to get n = 17 Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

Available with Beat the GMAT members only code

• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

• FREE GMAT Exam
Know how you'd score today for \$0

Available with Beat the GMAT members only code

• 5-Day Free Trial
5-day free, full-access trial TTP Quant

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

### Top First Responders*

1 Jay@ManhattanReview 67 first replies
2 Brent@GMATPrepNow 64 first replies
3 GMATGuruNY 44 first replies
4 Ian Stewart 23 first replies
5 Scott@TargetTestPrep 17 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 Scott@TargetTestPrep

Target Test Prep

211 posts
2 Max@Math Revolution

Math Revolution

94 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

90 posts
4 GMATGuruNY

The Princeton Review Teacher

69 posts
5 Jay@ManhattanReview

Manhattan Review

68 posts
See More Top Beat The GMAT Experts