A tree grows only 3/5 as fast as the one beside it.?

Question

A tree grows only 3/5 as fast as the one beside it. In four years the combined growth of the two trees is eight feet.
How much does the shorter tree grow in two years?
(a) Less than 2 feet (b) 2 feet (c) 2 1/2 feet

clear steps plz

Answer 1

(a) less than 2 feet:

let the shorter tree be a and the taller tree be b.

a = 3 units growth rate
b = 5 units growth rate

4 years later
a + b = 8 feet
a = 3 feet
b = 5 feet
4 years = 3 feet
2 years = 1.5 feet (less than 2 feet)

hope you understand =)

Answer 2

tree A grows by x
tree B grows by 3x/5= 0.6x
Combined growth is 0.6x+x= 1.6x

After 4 years, 1.6x=8ft
=> x = 8/1.6
= 5

After 4 years, tree A = 3ft
tree B = 5ft

If we suppose that the growth is linear, the at two years, theri combined height is a half of 8ft i.e. 4ft

=> Tree A = 1.5ft
Tree B= 2.5ft

The shorter tree will be 1.5ft i.e. less than 2ft, choice (b)

Answer 3

if they began to grow at tuesday and after 4 years
tuessday x 360 x 4:the year 2010

and 3/5 x 2010:1206
the answer is d) neither

Answer 4

x = rate of growth of the faster tree
3x/5 = rate of the slower tree
x + (3/5)x =combined rate = 8 ft / 4 yr.
5x + 3x = 5*8/4 ft/yr
x = 5*8/(4*8) ft/yr
2*(3x/5) = 2*3*5*8/(4*5*8) ft