# Rate Problems: Speed, Work, Pipes and Cistern Tricks and Formulas

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## Time, Speed and Distance

## Important Conversion Factors

## Average Speed

**If the distance is constant, then average speed is given by harmonic mean of two speeds**:- If the time is constant, then average speed is given by arithmetic mean of two speeds

## Relative Speed

### For Trains

### For Boats and Streams

## Time and Work

## Time & Work

- If A can do a piece of work in n days, then A՚s 1 day՚s work
- If A՚s 1 day՚s work then A can finish the work in n days.
- If A is thrice as good a workman as B, then: Ratio of work done by A and Ratio of times taken by to finish a work

## Pipes & Cisterns

- If a pipe can fill a tank in ‘x’ hours and another pipe can empty the full tank in ‘y’ hours then on opening both the pipes, the net part of the tank filled in 1 hour is