A freshly isolated sample of ⁹⁰Ywas found to have an activity of 4.3 × 10⁵ disintegrations per minute at 1:00 p.m. on December 3, 2006. At 2:15 p.m. on December 17, 2006, its activity was measured again and found to be 1.1 × 10⁴ disintegrations per minute. Calculate the half-life of ⁹⁰Y. Round your answer to 2 significant digits.