The Department of Commerce estimated that there were 53 million internet users in the country in 1999 and 90 million in 2002. Find an exponential function that the models the number of Internet users in year x, with x=0 corresponding to 1999.

Answer 1

you want

p = a e^(kt)
clearly p(0) = 53

p = 53 e^(kt)
p(3) = 90, so

53 e^(3k) = 90
e^(3k) = 90/53
3k = ln(90/53)
k = ln(90/53)/3 = 0.1765

so, we have

p(t) = 53 e^(.1765t)

Now you try the others, lest you be accused of homework dumping...