Naturally occurring magnesium has an atomic mass of 24.312 and consists of three isotopes. The major isotope is ²⁴Mg, natural abundance 78.99%, relative atomic mass 23.98504. The next most abundant isotope is ²⁶Mg, relative atomic mass 25.98259.

The third most abundant isotope is ²⁵Mg, whose natural abundance is in the ratio of 0.9083 to that of ²⁶Mg. Find the relative atomic mass of ²⁵Mg.