A certain forest covers an area of 2200 km2. Suppose that each year this area decreases by 4.75%. What will the area be after 10 years?

Answer 1

Hello Callie,

You can use the exponential growth formula:

B = A* (1+r)^t

A is the initial amount, B is the final amount at time t

t is how long it takes for the amount to go from A to B

r is either the growth rate or decay rate. It will be positive it there's growth from A to B, negative if decay from A to B

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The problem give you the initial area: A = 2200 km2.

It gives you t: t = 10 years

You're told that the area DECREASES every year, so this is decay, meaning r will be negative. Specifically:

r = 4.75% = 0.0475

To find B, you just plug everything in the formula I stated at the beginning:

B = 2200 (1-0.0475)¹⁰

You can set that up in your calculator and it will get you the answer.

Cheers!