Important Formulae: Speed, Time & Distance Notes | Study Quantitative Aptitude (Quant) - CAT

Time Speed and Distance

Speed = Distance / Time
1 kmph = 5/18 m/sec; 1 m/sec = 18/5 kmph

If the distance covered is constant then the average speed is the Harmonic Mean of the values (s₁, s₂, s₃….s_n)

If the time taken is constant then the average speed is the Arithmetic Mean of the values (s₁, s₂, s₃….s_n)

EduRev's Tip: Given that the distance between two points is constant, then
⇒ If the speeds are in Arithmetic Progression, then the times taken are in Harmonic Progression
⇒ If the speeds are in Harmonic Progression, then the times taken are in Arithmetic Progression
For Trains, time taken =
For Boats,
Speed_Upstream = Speed_Boat – Speed_River
Speed_Downstream = Speed_Boat + Speed_River
Speed_Boat = (Speed_Downstream + Speed_Upstream) / 2
Speed_River = (Speed_Downstream – Speed_Upstream) / 2
For Escalators, The difference between escalator problems and boat problems is that escalator can go either up or down.