The number of new members joining Facebook each year in the period from 2005 to the middle of 2008 can be modeled by = m(t) 12t2 20t+ 10 million members per year (0 sts 3.5), - where t is time in years since the start of 2005.+ What was the average number of new members joining Facebook each year from the start of 2005 to the start of 2007? x million members per year 4