Question

Please show work if you do, ( and get it right) I will make you brainliest!!!





During two years, the population of birds of an island became 7 times more than before. If the first year increase in the population was 40% , what was the percent increase of the second year?

Answer 1

Answer:

The percentage increase in bird population in the second years is 4%  .

Step-by-step explanation:

Given as :

During two years, the population of birds of an island became 7 times more than before.

The the percentage increase in first year = = $r_1$ =40%

Let The percentage increase in second year =  $r_2$ = r%

So, According to question

The initial population of bird = x

The increase population of bird =7 times before = 7 x

Now,

The increase population of bird = initial population of bird × (1+ $\dfrac{r_1}{100}$) ×  (1+ $\dfrac{r_2}{100}$)

Or, 7 x = x × (1+ $\dfrac{40}{100}$) ×  (1+ $\dfrac{r}{100}$)

Or, $\dfrac{7 x}{x}$ = 1.4 ×  (1+ $\dfrac{r}{100}$)

Or, 7 = 1.4 ×  (1+ $\dfrac{r}{100}$)

Or, $\dfrac{7 }{1.4}$ = (1+ $\dfrac{r}{100}$)

Or, 5 = (1+ $\dfrac{r}{100}$)

Or, (1+ $\dfrac{r}{100}$) = 5

Or, $\dfrac{r}{100}$ = 5 - 1

Or,  $\dfrac{r}{100}$ = 4

∴ r = 4 × 100

I.e r = 400

so, The percentage increase = r% = 4

Hence The percentage increase in bird population in the second years is 4%  . Answer