A truck covers a distance of 600 metres in 1 minute whereas a bus covers a distance of 32 km in 40 minutes. The ratio of their speeds is

Speed $=\frac{\text { Distance }}{\text { Time }}$

$\therefore$ Required ratio $=\frac{600}{1}: \frac{32000}{40}$

= 600 : 800 = 3 : 4