Many ancient tombs were cut from limestone rock that contained uranium. Since most such tombs are not well-ventilated, they may contain radon gas. In one study, the radon levels in a sample of 12 tombs in a particular region were measured in becquerels per cubic meter (Bq/m3). For this data, assume that x(over-bar)= 3,469 Bq/m3 and s= 1,135 Bq/m3. Use this information to estimate, with 95% confidence, the mean level of radon exposure in tombs in the region. Interpret the resulting interval.