Mathematics for IGCSE & O level - Proportion (Section 2 - No. 48)
The time taken to complete a journey varies inversely with the speed. If a journey takes 4 hours at 60 mph, how long would it take at 40 mph?
2 hours
3 hours
6 hours
8 hours
คำอธิบาย
t = k/s, so k = 4*60 = 240. t = 240/40 = 6 hours.