The expression 5.06x + 9.7 can be used to predict the average daily number of e-mail messages, in billions, in North America x years after 2000.

The expression 5.06x + 9.7 can be used to predict the average daily number of e-mail messages, in billions, in North America x years after 2000. Predict the average daily volume of e-mail messages in 2008 and 2009. What is the difference? Approximately how many e-mail messages do you get in a day. If this were constant, how many e-mails would you get in a year? Why do you think the use of e-mailing has increased?