3. The number of US. citizens aged 65 years and older from 1900 through 2050 is estimated to be growing at the rate ofR(t) = o. 063t2 0. 48t + 3. 87 (05 r s 15) million people/decade, where t is measured in decades, with t=0 corresponding to 1900. Show that the average rate of growth of the number of US. citizens aged 65 years and older between 2000 and 2050 will be about twice the average rate between 1950 and 2000