A certain forest covers an area of 1800 km^2. Suppose that each year this area decreases by 8.5% . What will the area be after 5 years? round your answer to the nearest square kilometer.

Question

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Answer 1

This is an excellent example of exponential decay! The formula you would use is:

y = a (1 - r)^t where a = initial value, r = rate of decay, and t = time, and y = amount left after "t" years

Our forest starts out at 1800 km^2 (our "a" value), it's area decrease at 8.5% (our "r" value), and we want to find the area left after 5 years (our "t" value):

y = 1800 (1 - .085)^5

y = 1800 (0.915)^5

y = 1,154 km^2