Build the formula, word problem, help!!

• August 31st 2010, 05:27 PM
NoPlaneOnSunday
Build the formula, word problem, help!!
n 1950, the population density of the United States was 42.6 people per sq mile and in 2000 it was 79.6 people per sq mile. Assuming the population density grew at a constant rate of change, find the function that gives the population density based on the number of years since 1950.

So far all I have gotten is y = .74x but I know I need it in y =.74x + b. I just can't figure out the +b part!

Also, would x = the year?

Thank you!
• August 31st 2010, 05:50 PM
pickslides
x will be the year.

$y = 0.74x+42.6$

where x=0 represents the year 1950.
• August 31st 2010, 06:12 PM
NoPlaneOnSunday
Thank you so much for your help - I don't know why this one was so hard for me!