In an effort to produce a formula for estimating the age of large free standing oak trees non-invasively, the girth a: (in inches) five feet off the ground of 15 such trees of known age 3; (in years) was measured. The sample data are summarized by the following information. 71.: 15 E$=3368 2y: 6496 Emy = 1,933,219 24:2 = 917,780 Eyz = 4,260,666 74 g a: g 395