Question

On my sister's 15th birthday, she was 159cm in height, having grown 6% since the year before. How tall was she the previous year?

Answer 1

GIVEN :

Height of the person on birthday = 159cm

Percentage grown since last year = 6%

Height of the person previous year = x

According to the problem,

159 = 100 + 6x /100

15900 = 106x

x = 15900/106

x = 150cm

Therefore, the height of the person previous year is 150cm.

Answer 2

Given:

Height on $\sf{15^{th}}$ birthday = 159 cm

Growth = 6%

Now:

Let the previous year height be 'x'.

Then:

Height on $\sf{15^{th}}$ birthday:

$\implies$ $\sf{159 = x \times \frac{(100 + 6)}{100}}$

$\implies$ $\sf{159 = x \times \frac{106}{100}}$

And:

$\implies$ $\sf{x = \frac{159 \times 100}{106}}$

$\implies$ $\sf{x = 1.5 \times 100}$

$\implies$ $\sf{x = 150}$

Therefore:

Final answer: 150 cm