trees Gmat prep

[alltimeacheiver]

When a tree was planted it was 4 feet. Its height increased by a constant amount each year for 6 years. After 6 years the tree was 1�5 taller than at the end of 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

[spallavi]

Hi,

I think the answer is d. 2/3

This is how I solved.
Lets say 'x' is the constant amount that the tree grows every year.
At the end of 4years, the tree's height is (4+4x).
At the end of 6 years, the tree's height is (4+6x).
At the end of 6years, the height is 1/5 more than what it was at 4years.
(4+6x) = (4+4x) + 1/5(4+4x)
Solving for x, x=2/3

Anyone disagree with the solution.
~Pallavi

[varungoel]

I got the same answer.

D

[Anurag@Gurome]

When a tree was planted it was 4 feet. Its height increased by a constant amount each year for 6 years. After 6 years the tree was 1�5 taller than at the end of 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

Say each year the height is increased by x feet.
Height at the end of 4th year = (4 + 4x) feet
Height at the end of 6th year = (4 + 6x) feet

According to question,
Height after 6th year = Height after 4th year + (1/5)*(Height after 4th year)

Thus, (6x + 2) = (4x + 4) + (1/5)*(4x + 4)
=> (4x + 4)/5 = 2x
=> (4x + 4) = 10x
=> 6x = 4
=> x = 2/3

The correct answer is D.