Are at least 10 percent of the people in Country X who are 65 years old or older employed?
(1) In country x, 11.3 percent of the population is 65 years old or older.
(2) In country x, of the population 65 years old or older, 20 percent of the men and 10 percent of the women are employed.
st(1) Is not Sufficient as we have no data about the employed people 65 years old and older.
st(2) Here it does not matter how many 65 years old and older people are there in country x; we need to find if the number of these people employed is equal or more than 10%? st(2) provides that out of 65-65+ people employed in country x, only possible Men+Women=People. Hence if we have more men, then the percentage portion of employed women 65-65+ is counted as the bigger portion, then the percentage portion of men is added. But we have both Men and Women portions 10+%, so we may assume that even if the number of Men is less than Women, or the number of Women is less than Men - we still have 10+% on both ends of 50% (if equal, more or less). The weighted average of these numbers will always be at least equal to 10%, as none of the represented values (Men, Women) is less than 10%.
st(2) Sufficient and answer B.
I am attaching the handy graph for estimation; hope this helps













