you can use its mass number, A , as an approximation of its atomic mass.
In this case, you will have
46
Ti → ma ≈ 46 u
47
Ti →ma≈47 u
48
Ti →ma≈48 u
49
Ti →ma≈49 u
50
Ti →ma≈50 u
Now, the average atomic mass of titanium is calculated by taking the weighted average of the atomic masses of its stable isotopes.
Simply put, each isotope
i
will contribute to the average atomic mass of the element in proportion to its decimal abundance, which is simply the percent abundance divided by
100
The decimal abundances for these five isotopes will be
46
Ti:
8.0/100= 0.080
47
Ti: 7.8/100=0.078
48
Ti: 73.4/100 =0.734
49
Ti: 5.5/100=0.055
50
Ti: 5.3/100=0.053
The average atomic mass of titanium will thus be avg. atomic mass =46 u ×0.080+47 u ×0.078
+48 u ×0.734+49 u × 0.055 + 50 u × 0.053
avg. atomic mass
= 47.923 u