Social Networks The percentage of people age 12 years and older using social network sites and/or services "several" times a day from 2009 through 2013 grew at the rate of R(t) = 5.921:\"'-158 (1 s t s 5) percent/year in year t, with t = 1 corresponding to 2009. The percentage of people age 12 years and older using social network sites and/or services in 2009 was 7%.'r (a) Find an expression giving the percentage of people age 12 years and older using social network sites and/or services in year t (1 s t s 5). (Round the coefcients to three decimal places.) X (b) According to this model, what percentage of people age 12 years and older used social network sites and/or services in 2013? (Round your answer to one decimal place.) %