For data shown in the article “Wikipedia: Modelling Wikipedia’s growth” at en.wikipedia.org, the number of English language articles inWikipedia was well approximated from 2001 to 2008 by ˆy = 22,700(2.1)x, where x is the time (in years) since January 1, 2001.

(a) Interpret the values 22,700 and 2.1 in this prediction equation.

(b) A plot in this article shows that the growth has been more linear than exponential since 2007. If the exponential equation had continued to hold, predict the number of English Wikipedia articles on January 1, 2016. Compare to the actual number of about 5 million, and explain the dangers of model extrapolation.