If

a country’s GDP doubles every 50 years, then on a ratio scale graph against time, it

will rise with an increasing slope.

If

Country C's GDP per capita rises from $2,500 to 7,500, and Country D's GDP per capita

rises from $6,000 to 18,000, the ratio of GDP per capita between the two

countries is unchanged.

Country

E is growing at the same percentage rate as Country F, but Country E is 3 times

richer than Country F. On a log scale graph against time, the gap between the

two lines will be constant.