Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 25 May 2017, 15:16

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# When a certain tree was first planted, it was 4 feet tall,

Author Message
TAGS:

### Hide Tags

Manager
Joined: 14 Oct 2008
Posts: 160
Followers: 1

Kudos [?]: 59 [0], given: 0

When a certain tree was first planted, it was 4 feet tall, [#permalink]

### Show Tags

07 Nov 2008, 10:12
20
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

65% (02:38) correct 35% (01:49) wrong based on 469 sessions

### HideShow timer Statistics

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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5
[Reveal] Spoiler: OA

Last edited by Bunuel on 14 Oct 2012, 02:10, edited 1 time in total.
SVP
Joined: 17 Jun 2008
Posts: 1553
Followers: 11

Kudos [?]: 264 [4] , given: 0

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 11:34
4
KUDOS
1
This post was
BOOKMARKED
D. 2/3

Say, the tree grows by x feet every year.

Then, 4 + 6x = (1+1/5)(4+4x)
or, x = 2/3
Manager
Joined: 15 Oct 2008
Posts: 106
Followers: 1

Kudos [?]: 9 [0], given: 0

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 11:54
scthakur wrote:
D. 2/3

Say, the tree grows by x feet every year.

Then, 4 + 6x = (1+1/5)(4+4x)
or, x = 2/3

Agree with scthakur. D is the answer.
SVP
Joined: 29 Aug 2007
Posts: 2476
Followers: 70

Kudos [?]: 774 [1] , given: 19

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 12:05
1
KUDOS
2
This post was
BOOKMARKED
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

There's something particular with the answer of this one which i don't understand, hence the posting.

height at the end of 6th yr = 4 + x + x + x + x + x + x = 4 + 6x
height at the end of 4th yr = 4 + x + x + x + x = 4 + 4x

2x/4 + 4x = 1/5
x/2 + 2x = 1/5
5x = 2 + 2x
x = 2/3
_________________

Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html

GT

SVP
Joined: 30 Apr 2008
Posts: 1874
Location: Oklahoma City
Schools: Hard Knocks
Followers: 42

Kudos [?]: 590 [13] , given: 32

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 13:48
13
KUDOS
2
This post was
BOOKMARKED
We have to read the question carefully to make sure we see that the end of the 6th year is being compared to the end of the 4th year. Also note that the tree grows by a constant amount each year. This is different than the same % each year.

Let x = the constant annual growth in feet.

4ft is the original height of the tree, so after the 6th year, we have

4 + x + x + x + x + x + x….aslo 4 + 6x

After the 4th year we have 4 + x + x + x+ x or 4 + 4x

Lets compare the two values algebraically as the problem does:

6th year is 1/5 taller than the 4th year.

The difference in growth from the 4th to the 6th year will be 1/5 (or 0.2) of the height after the 4th year.

So…(4+6x)-(4+4x) = 1/5(4+4x)…now solve for x

4 + 6x -4 – 4x = 4/5 + 4/5x
2x = 4/5 + 4/5x
Subtract 4/5x from both sides. I’ve changed 2x into 10/5x to easily do the subtraction of fractions.

10/5x – 4/5x = 4/5

6/5x = 4/5

Divide both sides by 6/5, which is the same as multiplying by 5/6

X = 4/5 * 5/6. (Reduce the 5’s or multiply out and) you have 20 / 30 or x = 2/3.

Hope a different approach may help someone else.

gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

There's something particular with the answer of this one which i don't understand, hence the posting.

_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a.

GMAT Club Premium Membership - big benefits and savings

Manager
Joined: 14 Oct 2008
Posts: 160
Followers: 1

Kudos [?]: 59 [0], given: 0

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 15:55
Thanks Jallen. Its a bit clear now. I was wondering how 1/5 taller led to 1+1/5 . The wordings are very difficult for this one. I would have thought its either 1/5th or addition of 1/5. I knew the height after 6 years could not be 1/5th of height after 4 years. So i thought it might be addition. But i could not really understand why its so peculiar with this qs, i have not seen any other qs of this type. Is there any other similar example anyone has seen so far ?
VP
Joined: 05 Jul 2008
Posts: 1409
Followers: 39

Kudos [?]: 388 [2] , given: 1

Re: 4 feet tall tree ? [#permalink]

### Show Tags

07 Nov 2008, 19:01
2
KUDOS
x be the height increase every year

at end of 6 yrs it is 4+6x

4 yrs it is 4+4x

4+6x = 4+4x + 1/5 (4+4x) -> 2x = 1/5 (4+4x) -> 10x = 4+4x -> 6x=4 -> x=2/3
Manager
Joined: 17 Aug 2009
Posts: 229
Followers: 5

Kudos [?]: 254 [0], given: 25

Re: 4 feet tall tree ? [#permalink]

### Show Tags

01 Dec 2009, 23:36
Let the tree increase by a constant amount of x
Height after 6 yrs = 4 + 6x
Height after 4 years = 4 + 4x
Therefore, from statements

4+6x = 1/5 (4+4x) + 4+4x
X=2/3
Senior Manager
Joined: 20 Jul 2010
Posts: 264
Followers: 2

Kudos [?]: 87 [0], given: 9

Re: 4 feet tall tree ? [#permalink]

### Show Tags

23 Sep 2010, 17:27
1/5th taller than 4th year....i missed taking difference while taking the exam. Nice question
_________________

If you like my post, consider giving me some KUDOS !!!!! Like you I need them

Math Expert
Joined: 02 Sep 2009
Posts: 38882
Followers: 7733

Kudos [?]: 106128 [7] , given: 11607

Re: 4 feet tall tree ? [#permalink]

### Show Tags

23 Sep 2010, 22:13
7
KUDOS
Expert's post
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

There's something particular with the answer of this one which i don't understand, hence the posting.

Let the rate of increase be $$x$$ feet per year.

At the end of the 4th year the height was $$4+4x$$ and at the of the 6th year the height was $$4+6x$$, which was "1/5 taller than it was at the end of the 4th year" --> $$(4+4x)+\frac{1}{5}(4+4x)=4+6x$$ --> $$\frac{1}{5}(4+4x)=2x$$ --> $$x=\frac{2}{3}$$.

_________________
Senior Manager
Joined: 31 Mar 2010
Posts: 414
Location: Europe
Followers: 2

Kudos [?]: 45 [0], given: 26

Re: 4 feet tall tree ? [#permalink]

### Show Tags

10 Oct 2010, 06:39
I fell in the trap yesterday. I read that it was 1/5" taller than at the end of year 4.

Therefore I wrote: 4+6x = 4+4x+1/5 and couldn't figure out the answer nor my error.
Manager
Joined: 06 Jun 2011
Posts: 149
Followers: 1

Kudos [?]: 66 [1] , given: 15

Re: 4 feet tall tree ? [#permalink]

### Show Tags

31 Aug 2011, 23:50
1
KUDOS
Lets concise equation a bit more.
if x is the constant growth then difference between end of 6th year and end of 4th year
is 2x. So
2x=(4+4x)/5
10x=4+4x
6x=4
x=2/3
Intern
Joined: 15 Jul 2012
Posts: 9
Location: United States
Schools: Booth '16, ISB '15
GPA: 3.37
WE: Military Officer (Aerospace and Defense)
Followers: 0

Kudos [?]: 13 [0], given: 0

Re: When a certain tree was first planted, it was 4 feet tall, [#permalink]

### Show Tags

13 Oct 2012, 20:08
In the question stem it is 1/5.So how does one know that they are trying to say 1/5th.Or is this a frequent trap?
Manager
Joined: 20 Jun 2012
Posts: 103
Location: United States
Concentration: Finance, Operations
GMAT 1: 710 Q51 V25
Followers: 1

Kudos [?]: 42 [1] , given: 52

Re: When a certain tree was first planted, it was 4 feet tall, [#permalink]

### Show Tags

10 Jun 2013, 09:06
1
KUDOS
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

According to my method, I got a totally different answer. I am comfortable with all the explanations to this question but please help me finding flaw in my solution, here it is:

I considered it as a A.P. whose first term is 4.

I supposed 4th term to be 5x. Hence 6th term will me (5x+5x/5)=6x

as per A.P. formula [n-th term = a+(n-1)d]

4th term = 5x = 4+3d
6th term = 6x = 4+5d

After solving these equation for "d", I got d=4/7. What am I doing wrong ???
_________________

Forget Kudos ... be an altruist

Intern
Joined: 14 May 2013
Posts: 12
Followers: 0

Kudos [?]: 17 [1] , given: 3

Re: When a certain tree was first planted, it was 4 feet tall, [#permalink]

### Show Tags

10 Jun 2013, 23:40
1
KUDOS
stunn3r wrote:
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

According to my method, I got a totally different answer. I am comfortable with all the explanations to this question but please help me finding flaw in my solution, here it is:

I considered it as a A.P. whose first term is 4.

I supposed 4th term to be 5x. Hence 6th term will me (5x+5x/5)=6x

as per A.P. formula [n-th term = a+(n-1)d]

4th term = 5x = 4+3d
6th term = 6x = 4+5d

After solving these equation for "d", I got d=4/7. What am I doing wrong ???

Here is something wrong

the 1st term is 4 and after a year it will be 4+d and so on after the 4th year it will be 4+4d

5th term will be = 5x = 4+4d
and 7th term will be 6x = 4+6d

and after solving both the equations d = 2/3 .

Ans : D
_________________

Chauahan Gaurav
Keep Smiling

Manager
Joined: 20 Jun 2012
Posts: 103
Location: United States
Concentration: Finance, Operations
GMAT 1: 710 Q51 V25
Followers: 1

Kudos [?]: 42 [0], given: 52

Re: When a certain tree was first planted, it was 4 feet tall, [#permalink]

### Show Tags

10 Jun 2013, 23:43
ichauhan.gaurav wrote:
stunn3r wrote:
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

According to my method, I got a totally different answer. I am comfortable with all the explanations to this question but please help me finding flaw in my solution, here it is:

I considered it as a A.P. whose first term is 4.

I supposed 4th term to be 5x. Hence 6th term will me (5x+5x/5)=6x

as per A.P. formula [n-th term = a+(n-1)d]

4th term = 5x = 4+3d
6th term = 6x = 4+5d

After solving these equation for "d", I got d=4/7. What am I doing wrong ???

Here is something wrong

the 1st term is 4 and after a year it will be 4+d and so on after the 4th year it will be 4+4d

5th term will be = 5x = 4+4d
and 7th term will be 6x = 4+6d

and after solving both the equations d = 2/3 .

Ans : D

ahh ... correct .. Thank You ..
_________________

Forget Kudos ... be an altruist

Intern
Joined: 07 Feb 2012
Posts: 13
Concentration: Strategy
GMAT 1: 720 Q48 V41
Followers: 0

Kudos [?]: 1 [1] , given: 1

Re: 4 feet tall tree ? [#permalink]

### Show Tags

24 Jun 2013, 08:13
1
KUDOS
Bunuel wrote:
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

There's something particular with the answer of this one which i don't understand, hence the posting.

Let the rate of increase be $$x$$ feet per year.

At the end of the 4th year the height was $$4+4x$$ and at the of the 6th year the height was $$4+6x$$, which was "1/5 taller than it was at the end of the 4th year" --> $$(4+4x)+\frac{1}{5}(4+4x)=4+6x$$ --> $$\frac{1}{5}(4+4x)=2x$$ --> $$x=\frac{2}{3}$$.

Hi Bunuel,

For such problems, I am not sure whether the increase is by a factor(multiplication) or by an amount(addition). In this problem, I actually took it as multiplication and got the below equation

4a^6=4a^4(1+1/5) .. where a is the amount it increases by every year.

How do I differentiate between a multiplication increase and an addition increase?

Thanks.
Math Expert
Joined: 02 Sep 2009
Posts: 38882
Followers: 7733

Kudos [?]: 106128 [0], given: 11607

Re: 4 feet tall tree ? [#permalink]

### Show Tags

25 Jun 2013, 02:24
Expert's post
1
This post was
BOOKMARKED
deliverance wrote:
Bunuel wrote:
gameCode 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 the 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?

A. 3/10
B. 2/5
C. 1/2
D. 2/3
E. 6/5

There's something particular with the answer of this one which i don't understand, hence the posting.

Let the rate of increase be $$x$$ feet per year.

At the end of the 4th year the height was $$4+4x$$ and at the of the 6th year the height was $$4+6x$$, which was "1/5 taller than it was at the end of the 4th year" --> $$(4+4x)+\frac{1}{5}(4+4x)=4+6x$$ --> $$\frac{1}{5}(4+4x)=2x$$ --> $$x=\frac{2}{3}$$.

Hi Bunuel,

For such problems, I am not sure whether the increase is by a factor(multiplication) or by an amount(addition). In this problem, I actually took it as multiplication and got the below equation

4a^6=4a^4(1+1/5) .. where a is the amount it increases by every year.

How do I differentiate between a multiplication increase and an addition increase?

Thanks.

We are told that "the height of the tree increased by a constant amount each year" so it must be addition. If it were multiplication then the increase wouldn't be the same each year.

Hope it's clear.
_________________
Manager
Joined: 24 Jan 2013
Posts: 79
Followers: 5

Kudos [?]: 144 [0], given: 6

When a certain tree was first planted, it was 4 feet tall, a [#permalink]

### Show Tags

14 Jul 2013, 03:54
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 the 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?

A) 3/10
B) 2/5
C) 1/2
D) 2/3
E) 6/5
Math Expert
Joined: 02 Sep 2009
Posts: 38882
Followers: 7733

Kudos [?]: 106128 [0], given: 11607

Re: When a certain tree was first planted, it was 4 feet tall, a [#permalink]

### Show Tags

14 Jul 2013, 03:57
johnwesley 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 the 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?

A) 3/10
B) 2/5
C) 1/2
D) 2/3
E) 6/5

Merging similar topics. Please refer to the solutions above.
_________________
Re: When a certain tree was first planted, it was 4 feet tall, a   [#permalink] 14 Jul 2013, 03:57

Go to page    1   2    Next  [ 27 posts ]

Similar topics Replies Last post
Similar
Topics:
4 A snail, climbing a 20 feet high wall, climbs up 4 feet on the first 4 14 Jun 2016, 07:37
3 A farmer is planting a row consisting of 4 unique apple trees and 4 un 3 22 Jul 2016, 00:21
1 When a certain tree was first planted, it was 4 feet tall 3 30 Nov 2012, 03:26
10 A certain kudzu plant was 11 feet long on the day it was 8 24 Oct 2016, 06:33
146 When a certain tree was first planted, it was 4 feet tall 15 06 Feb 2017, 19:58
Display posts from previous: Sort by