Question

At the beginning of an environmental study, a forest covered an area of 1500km2 . since then, this area has decreased by 7.1% each year. let t be the number of years since the start of the study. let y be the area that the forest covers in km2 . write an exponential function showing the relationship between y and t .

Answer 1

y on t=o is 1500
decreasing with 7,1% every year means multiplying with 100% - 7,1% = 92,9%

y= (value on t=0) x 92,9^t
y = 1500 · 92,9^t

the exponential function you're looking for is: y = 1500 · 92,9^t