START's reply

===> How many people live in Africa's fifth largest country?

I know that Africa's fifth largest country is Niger (source: The World Factbook).

Using this information, I determined how many people live in Niger:

Niger

flag

Population:
17,466,172 (July 2014 est.)
country comparison to the world: 63

Age structure:
0-14 years: 49.8% (male 4,387,785/female 4,308,312)
15-24 years: 18.4% (male 1,586,720/female 1,626,457)
25-54 years: 25.9% (male 2,261,287/female 2,266,576)
55-64 years: 3.3% (male 294,446/female 274,268)
65 years and over: 2.6% (male 234,079/female 226,242) (2014 est.)
population pyramid:

Source: The World Factbook