SOLUTION
We want to use the model below to solve the question
(a) Since x = 0 represents 1990, the number of travelers in 1990 becomes

We have

Hence the answer is 44.8 million to the nearest tenth
(b) 2000. From 1990 to 2000 is 10 years. So, we will substitute 10 for x into the function, we have

Hence the answer is 63.4 million to the nearest tenth
(c) From 1990 to 2009 is 19 years. Substituting 19 for x, we have

Hence the answer is 66.3 to the nearest tenth