Answer
Atomic mass of Nickel = $58.6934amu$
Work Step by Step
Mass of $^{58}Ni = 57.9353 amu$
% abundance of $^{58}Ni = 68.08\%$
Mass of $^{60}Ni = 59.9308 amu$
% abundance of $^{60}Ni = 26.22\%$
Mass of $^{61}Ni = 60.9311amu$
% abundance of $^{61}Ni = 1.14\%$
Mass of $^{62}Ni = 61.9283 amu$
% abundance of $^{62}Ni = 3.63\%$
Mass of $^{64}Ni = 63.9280amu$
% abundance of $^{64}Ni =0.93\%$
The atomic mass of an element is the weighted average of the constituent isotopes.
Therefore, atomic mass of Nickel = $0.6808(57.9353amu)+0.2622(59.9308amu)+0.0114(60.9311amu)+0.0363(61.9283amu)+0.0093(63.9280amu)$
Atomic mass of Nickel = $58.6934amu$
