What is the population of the city A?
I. The ratio of the population of males and females in city A is 27 : 23 and the difference between their population is 100000.
II. The population of city A is 80% of that of city B. The difference of population of city A and city B is 312500.

Statement I : Lat males in city A = $$27x$$ and females in city A = $$23x$$

=> $$27x - 23x = 1,00,000$$

=> $$x = \frac{1,00,000}{4} = 25,000$$

$$\therefore$$ Total population of city A = $$27x + 23x = 50x$$

= $$50 \times 25,000 = 12,50,000$$

=> Statement I alone is sufficient.

Statement II : Let population of city B = $$100x$$

=> Population of city A = $$\frac{80}{100} \times 100x = 80x$$

=> $$100x - 80x = 3,12,500$$

=> $$x = \frac{3,12,500}{20} = 15,625$$

$$\therefore$$ Population of city A = $$80 \times 15,625 = 12,50,000$$

=> Statement II alone is sufficient.

$$\therefore$$ Either statement alone is sufficient.