Exponential Function Model

[severe]

The number of cell phones in use worldwide grew from 11 million in 1990 to 319 million in 1998. Let t represent the number of years since 1990. Thus, at t=0 years the number of cell phones in use was 11 million.

a) Find the exponential function that models the number of cell phones in use at any time t.
b) Predict the number of cell phones in use in 2014.

It seems really simple but I'm having a really hard time figuring out how to model this. Any help would be greatly appreciated!

 

[stapel]

The number of cell phones in use worldwide grew from 11 million in 1990 to 319 million in 1998. Let t represent the number of years since 1990. Thus, at t=0 years the number of cell phones in use was 11 million.

a) Find the exponential function that models the number of cell phones in use at any time t.
b) Predict the number of cell phones in use in 2014.

It seems really simple but I'm having a really hard time figuring out how to model this.

Try using what they've given you. They've provided two data points; namely, the points formed by the two values of t and the two corresponding values of cell-phone volumes (let's give them the variable "C"). They've told you that C is related to t in terms of an exponential function, so you know that the relation will be of the form C(t) = Ae^kt for some values of A and k.

So you've plugged the given points into the given formula, creating a system of two equations in two unknowns. You've solved for the two unknowns, and... then what?

Please be complete. Thank you!