Solution(By Examveda Team)

For state Q:
Male population below poverty line = 2.4 million
Let the female population below poverty line be $$x$$ million
Then,
$$\eqalign{ & 3 : 5 = 2.4 : x \cr & \Rightarrow x = \frac{5 \times 2.4}{3} \cr & \Rightarrow x = 4 \cr} $$
∴ Total population below poverty line
= (2.4 + 4) million
= 6.4 million
Let the total population of Q be $$p$$
Then,
$$\eqalign{ & 25\% \text{ of }p = 6.4 \text{ million} \cr & \Rightarrow \frac{25}{100}\times p = 6.4 \cr & \Rightarrow p = 6.4\times4 \cr & \Rightarrow p = 25.6 \text{ million} \cr} $$

For state T:
Male population below poverty line = 6 million
Let the female population below poverty line be $$y$$ million
Then,
$$\eqalign{ & 5 : 3 = 6 : y \cr & \Rightarrow y = \frac{3\times6}{5} \cr & \Rightarrow y = 3.6 \cr} $$
∴ Total population below poverty line
= (6 + 3.6) million
= 9.6 million
Let the total population of state T be $$q$$
Then,
$$\eqalign{ & 15\% \text{ of } q = 9.6 \text{ million} \cr & \Rightarrow \frac{15}{100} \times q = 9.6 \cr & \Rightarrow q = 9.6\times \frac{20}{3} \cr & \Rightarrow q = 64 \text{ million} \cr & \therefore \text{Required ratio} \cr & = \frac{p}{q} \cr & = \frac{25.6}{64} \cr & = 0.4 \cr & = \frac{4}{10} \cr & = \frac{2}{5} \cr & = 2 : 5 \cr & \text{So, the ratio of } \text{Q}:\text{T} = 2:5 \cr} $$