\(T_P=10\) minute \(\quad T_Q=15\) minute
After \(30\) minute \(P\) has gone \(3\) half lives and \(Q=2\) half lives
\(N_P=N_0\left(\frac{1}{2}\right)^3\) \(\quad N_Q=N_0\left(\frac{1}{2}\right)^2\)
\(N_P: N_Q=1: 2\)
\(\text { or } \frac{N_P}{N_Q}=0.5\)