The UN Food and Agriculture Organization estimates that $4.3$ % of the world's natural forests existing in 1990 were gone by the end of the decade. Suppose that in 1990, the world's forest cover stood at $3820$ million hectares. (The actual value was 4077 millian hectares.)

(a) Given the forest cover of $3820$ million hectares, how many millions of hectares of forest were lost during the 1990s?
help (numbers)

(b) Based on your work in (a), how many million hectares of natural forests existed in the year 2000?
help (numbers)

(c) Write an exponential formula approximating the number of million hectares of natural forest in the world $t$ years after 1990 if the value in 1990 is $3820$ million hectares.
$P = f(t) =$ help (formulas)

(d) What was the annual percent decay rate during the 1990s?
% (Round to 0.01%) help (numbers)