Let p be the percentage of major firms that perform drug tests on employees and/or job applicants at t years since 1980. Some pairs ot values ot t and p are shown in the table to the right. (a) Create a graph ot the data. (b) Are the variables t and p linearly related? Explain. t (years) 5 8 10 13 16 19 23 25 p (percent) 20 50 70 78 75 67 62 70