Arithmetic Problem

[lokesh r]

A certain tree when planted was 4 ft tall, tree increased in height 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 4 th year. By how feet did the height of tree increase each year.

A) 3/20
B) 2/5
c) 1/2
d) 2/3
e) 6/5

Ans..D

Can anyone check what is mistake in my equation phrased below.

4, 4+x, 4+2x, 4+3x, 4+4x, 4+5x the height of tree in 6 years respectively.

Given 4+5x= (4+3x)+ 1/5(4+3x)

Solve for x, but i am getting value of x which is not listed in options above.

[vijaynaik]

it's for next 6 years.

So if 4 is the starting height then for next 6 years it's 4+x (After 1styear),4+2x,4+3x,4+4x,4+5x,4+6x(after 6th year).

So the equation is 4+6x = 4+4x + 1/5[4+4x];
which will give x = 2/3

[lokesh r]

it's for next 6 years.

So if 4 is the starting height then for next 6 years it's 4+x (After 1styear),4+2x,4+3x,4+4x,4+5x,4+6x(after 6th year).

So the equation is 4+6x = 4+4x + 1/5[4+4x];
which will give x = 2/3

I got it..thanks very much.