## anonymous one year ago A certain forest covers an area of 4200km2. Suppose that each year this area decreases by 5.5%. What will the area be after 12 years?

1. campbell_st

are you working on sequences and series...?

2. anonymous

idk @campbell_st

3. campbell_st

ok... makes it hard to explain, if you don't know. do you know how to use the compound interest formula..?

4. anonymous

yes but i need it to decrease and idk how to do that one @campbell_st

5. Mertsj
6. campbell_st

ok... so the compound interest formula can be converted to a depreciation formula by changing the sign inside the brackets from + to -

7. campbell_st

the formula I know is $A = P(1 + \frac{r}{100})^n$ you can use $A = P(1 - \frac{r}{100})^n$

8. campbell_st

r = 5.5 P = 4200 and n = 12 hope it helps

9. anonymous

thank you i will try it @campbell_st

10. anonymous

i cant get it right @campbell_st

11. campbell_st

why, what do you get as an answer..?