A radioactive substance decays exponentially: The mass at time t is m(t) = m(0)ekt, where m(0) is the initial mass and k is a ne
gative constant. The mean life M of an atom in the substance is M = −k [infinity] tekt dt. 0 For a radioactive isotope, the value of k is −0.000192. Find the mean life of the isotope's atom. (Round your answer to one decimal place.) yr