In 1997 there were 55.31 million cell phone subscribers, and in 2004 there were 182.14 million cell phone subscribers. Find a linear equation to predict the number of cell phone subscriber, where t is the number of years since 1990. Round all numbers to two decimal places.

Question

anonymous · Answer

Do you know how to find the equation of a line using 2 points?  Well, that's what we've got here.  
Your points are (7, 55.31) and (14, 182.14).   Why the 7? or 14? Well, they are the number of years since 1990.   Now find the slope of the line using the formula, then use the point-slope formula using only one of the points and round to 2 decimal places.