The age of water or wine may be determined by measuring its radioactive tritium () content. Tritium, present in a steady state in nature, is formed primarily by cosmic irradiation of water vapor in the upper atmosphere, and it decays spontaneously by a first order process witha half-life of 12.5 years. The formation reaction does not occur H31 significantly inside a glass bottle at the surface of the earth. Calculate the age of a suspected vintage wine that is 20 % as radioactive as a freshly bottled specimen