Question

A tree was planted three years ago. The rate of its growth is 30% per annum. If at present, the height of the tree is 670 cm, what was it when the tree was planted?

Answer 1

Answer:

ANSWER IS 305 CM. THIS IS THE CORRECT ANSWER

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Answer 2

Answer:

The tree was planted at the height of 305cm

Step-by-step explanation:

Rate of growth of tree per annum (R) = 30%

Present height of the tree (A) = 670cm

Total time is taken by the tree (T) = 3 years

Let Initia's height of the tree (P) = x cm

Using the formula of compound interest :

$\[A = P{\left( {1 + \frac{R}{{100}}} \right)^t}\]$

$\[\begin{gathered} 670 = x{\left( {1 + \frac{{30}}{{100}}} \right)^3} \hfill \\ 670 = x{\left( {\frac{{130}}{{100}}} \right)^3} \hfill \\ x = 670{\left( {\frac{{100}}{{130}}} \right)^3} \hfill \\ x = 305cm \hfill \\ \end{gathered} \]$

Therefore, the initial height of the tree was 305cm.