The document Important Formulae: Speed, Time & Distance CAT Notes | EduRev is a part of the Quant Course Quantitative Aptitude (Quant).

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**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 Harmonic Mean of the values (s_{1}, s_{2}, s_{3}….s_{n})

If the time taken is constant then the average speed is Arithmetic Mean of the values (s_{1}, s_{2}, s_{3}….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_{Rive}_{r}

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.

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