Answer:
51.51 amu .
Explanation:
The atomic mass 52 amu has percentage of 79.5%
The atomic mass 49 amu has percentage of 8%
The atomic mass 50 amu has percentage of 12.5 %
Average atomic pass will be weighted average of their atomic weights
= 52 x .795 + 49 x .08 + 50 x .125
= 41.34 + 3.92 + 6.25
= 51.51 amu .