|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 07 Dec 2006
Posts: 169
Followers: 1
Kudos [?]:
12
[0], given: 0
|
When a certain tree was first planted, it was 4 feet tall, [#permalink]
 28 Jan 2008, 16:29
When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? 
|
|
|
|
|
|
|
VP
Joined: 09 Jul 2007
Posts: 1114
Location: London
Followers: 4
Kudos [?]:
55
[0], given: 0
|
Re: GMATprep : Height of the tree [#permalink]
28 Jan 2008, 19:03
GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? Detailed answer. annual fixed length: x length when planted: 4 year 1: 4+x year 2: 4+2x year 3: 4+3x year 4: 4+4x year 5: 4+5x year 6: 4+6x so (4+6x)=4+4x+(4+4x)/5 (4+6x)*5=24+24x 20+30x=24+24x 6x=4 x=2/3
|
|
|
|
|
|
Director
Joined: 20 Aug 2007
Posts: 852
Location: Chicago
Schools: Chicago Booth 2011
Followers: 8
Kudos [?]:
77
[1] , given: 1
|
Re: GMATprep : Height of the tree [#permalink]
28 Jan 2008, 19:15
1
This post received
KUDOS
GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? The tree's growth is an arithmetic sequence since the growth is constant. a(n) = a0 + nd, where d is the difference we are looking for and a0 = 4 a(6) = 4 + 6d and a(4) = 4 + 4d, and we know that a(6) = 1.2a(4) 4 + 6d = 1.2(4 + 4d) ---> 1.2d = 0.8 ---> d = 2/3 ft or 8 inches growth per year
|
|
|
|
|
|
Senior Manager
Joined: 26 Jan 2008
Posts: 267
Followers: 2
Kudos [?]:
58
[0], given: 1
|
Re: GMATprep : Height of the tree [#permalink]
28 Jan 2008, 19:23
GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? original height of tree = 4 feet height gained in the past 6 years = 1/5th of the original height = (1/5) * 4 feet = 0.8 feet height gained EACH YEAR = 0.8 / 6 = 0.133 feet
_________________
My GMAT debrief
|
|
|
|
|
|
Director
Joined: 20 Aug 2007
Posts: 852
Location: Chicago
Schools: Chicago Booth 2011
Followers: 8
Kudos [?]:
77
[0], given: 1
|
Re: GMATprep : Height of the tree [#permalink]
28 Jan 2008, 20:44
incognito1 wrote: GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? original height of tree = 4 feet height gained in the past 6 years = 1/5th of the original height = (1/5) * 4 feet = 0.8 feet height gained EACH YEAR = 0.8 / 6 = 0.133 feet It's gained 1/5 of the height from year 4 to year 6, not from year 0 to year 6.
|
|
|
|
|
|
Senior Manager
Joined: 26 Jan 2008
Posts: 267
Followers: 2
Kudos [?]:
58
[0], given: 1
|
Re: GMATprep : Height of the tree [#permalink]
28 Jan 2008, 21:32
sonibubu wrote: incognito1 wrote: GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? original height of tree = 4 feet height gained in the past 6 years = 1/5th of the original height = (1/5) * 4 feet = 0.8 feet height gained EACH YEAR = 0.8 / 6 = 0.133 feet It's gained 1/5 of the height from year 4 to year 6, not from year 0 to year 6. sonibubu, you're right -- it's comparing 6th year to 4th year, so an arithmetic sequence was required
_________________
My GMAT debrief
|
|
|
|
|
|
Director
Joined: 01 May 2007
Posts: 809
Followers: 1
Kudos [?]:
37
[0], given: 0
|
Re: GMATprep : Height of the tree [#permalink]
29 Jan 2008, 20:05
Agree with Ravshonbek. 2/3 is the answer. Starts at 4ft year 1 4+n year 2 4+n+n year... Two equations... 4+4n =x 4+6n = 1/5x + x Solve for n. n = 2/3 Ravshonbek wrote: GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? Detailed answer. annual fixed length: x length when planted: 4 year 1: 4+x year 2: 4+2x year 3: 4+3x year 4: 4+4x year 5: 4+5x year 6: 4+6x so (4+6x)=4+4x+(4+4x)/5 (4+6x)*5=24+24x 20+30x=24+24x 6x=4 x=2/3 |
|
|
|
|
|
CEO
Joined: 29 Mar 2007
Posts: 2618
Followers: 13
Kudos [?]:
142
[0], given: 0
|
Re: GMATprep : Height of the tree [#permalink]
30 Jan 2008, 11:13
GHIBI wrote: When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year? Could you please explain in detail? 4+6x=1.2(4+4x) --> 1.2 --> 12/10 --> 6/5 4+6x=24/5+24/5x --> 20+30x=24+24x --> 6x=4 ---> x=2/3
|
|
|
|
|
|
|
Re: GMATprep : Height of the tree
[#permalink]
30 Jan 2008, 11:13
|
|
|
|
|
|
|
|
|
Similar topics |
Author |
Replies |
Last post |
|
Similar
Topics:
|
 |
|
|
When a certain tree was first planted, it was 4 feet tall,
|
themagiccarpet |
3 |
16 Nov 2005, 03:03 |
|
|
|
|
When a certain tree was first planted, it was 4 feet tall,
|
myc2004 |
1 |
24 Apr 2006, 18:37 |
|
|
|
|
When a certain tree was first planted, it was 4 feet tall,
|
lan583 |
2 |
02 Aug 2006, 17:06 |
|
|
|
|
when a certain tree was first planted, it was 4 feet tall,
|
cejismundo |
1 |
17 Oct 2006, 20:31 |
|
|
|
|
When a certain tree was first planted, it was 4 feet tall,
|
tarek99 |
2 |
07 Dec 2007, 09:15 |
|
|
|
|
|
|
close
