The average atomic mass recorded on the periodic table for cobalt is 58.933 u. This indicates that the most abundant isotope of cobalt is. A newly discovered element, X, has two naturally occurring isotopes. 93.5 percent of the sample is an isotope with a mass of 268.9 u, and 6.5 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?