Since \(b \propto a^3\), therefore \(b = ka^3\) [where \(k\) is a non-zero constant] Given that \(a\) increases in the ratio 2:3, Let the initial value of \(a = 2m\) and the increased value = \(3m\) ∴ Before the increase, \(b = k \cdot (2m)^3 = 8km^3\) After the increase, \(b = k \cdot (3m)^3 = 27km^3\) ∴ The ratio of increase in \(b = \frac{8km^3}{27km^3} = 8 : 27\) ∴ \(b\) increases in the ratio 8:27.