Cosmic rays bombard the CO2 in the atmosphere and, by nuclear reaction, cause the formation of the radioactive carbon isotope 14C6. This isotope has a half-life of 5730 years. It mixes into the atmosphere uniformly and is taken up in plants as they grow. After a plant dies, the 14C decays over the ensuing years. How old is a piece of wood that has a 14C content which is only 9 percent as large as the average 14C content of new-grown wood?