Cell Subscribers

Question

The number of cell phone subscribers in the U.S. reached 256 million in 2008, up from 34 million in 1995. Find the equation of the line that depicts this info and use the equation to estimate the number of cell phone subscribers in the U.S. in 2012.

Answer 1

Hi Jane,

 

This isn't a great question because you don't know if the number of cell phone subscribers went up by the same amount each year, or if maybe twice as many people signed up for cell phones during the last year compared to the first year.

 

Since we don't know, we'll assume the easiest:  the number of cell phone subscribers went up by the same amount each year.

 

Then, (N2 - N1) / (Y2 - Y1) = S

 

Where N2 = the number of cell phone subscribers in the last year

and N1 = the number of cell phone subscribers in the first year

and Y2 = the last year

and Y1 = the first year

and S = the number of new cell phone subscribers each year

 

Then (256 million - 34 million) / (2008 - 1995) = S

 

         222 million / 13 = S

 

        S = 17.1 million new subscribers per year

 

Now you can use this information to figure out the new N2 if N1 = 256 million and Y2 = 2012 and Y1 = 2008 and S = 17.1 million.

 

Have fun.

 

Dan