What percent of the residents of Town X was born in Town X?
Statement 1: Of the male residents of town X, 40 percent were not born in Town X.
Let all male residents = m
Male residents not born in town X = 40% of m = 0.4m
Male residents born in town X = 60% of m = 0.6m
We do not know the value for females that were born in town X, so, we cannot estimate the total percent of residents that were born in town X.
Hence, statement 1 is NOT SUFFICIENT.
Statement 2: Of the female residents of town X, 60 percent were born in town X.
Let all females = f
Female residents not born in town X = 40% of 'f' = 0.4f
Female residents born in town X = 60% of 'f' = 0.6f
Also, we do not know the value for males that were born in town X, so therefore, we cannot find the total percentage of residents that were born in town X.
Hence, statement 2 is NOT SUFFICIENT.
Combining both statements together:
Total percentage of residents of town X who were born in town X =
$$=\frac{male+female\ residents\ born\ in\ town\ X}{total\ male+female\ residents\ in\ town\ X}\cdot\frac{100}{1}$$
$$=\frac{0.6m+0.6f}{m+f}\cdot\frac{100}{1}$$ $$=\frac{0.6\left(m+f\right)}{\left(m+f\right)}\cdot\frac{100}{1}=0.6\cdot\frac{100}{1}=60\%$$
Conclusively, both statements combined together are SUFFICIENT.
Answer = option C
