The population of starlings in Lower Fremont was 20,000 in 1962. In 2004 the population is 160,000. How do you calculate the percentage rate of starling population growth in Lower Fremont since 1962?

Mar 28, 2016

7% over 42 years

Explanation:

Rate of growth with this wording is based on :

$\left(\text{count of now" - "count of past") /("count of past}\right)$

Note that the time interval is critical for any further calculations so it must be declared.

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Time interval is: 2004-1962 in years $= 42$

So we have $\frac{160000 - 20000}{20000}$ for 42 years

$= \frac{140000}{20000}$

Using the shortcut method divide the bottom number (denominator) into the top number (numerator) and then multiply by 100 giving:

$7 \text{ }$ But this needs to let people know this is a percentage so we write:

7% over 42 years