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Topic

Speed, Distance and Time

Speed, distance and time questions connect how far something travels, how long it travels for, and its speed.

Topic explanation

Speed tells you how much distance is covered in one unit of time, such as kilometres per hour.

Before calculating, choose the fact you need: distance = speed × time, speed = distance divided by time, or time = distance divided by speed.

Most National 3 questions use short journeys with friendly numbers. Write the formula first.

Quick methods

Distance
Distance = speed × time
Speed
Speed = distance divided by time
Time
Time = distance divided by speed
Check units
Use hours with km/h unless the question says otherwise.

Worked examples

Example 1

A cyclist travels at 12 km/h for 2 hours. How far do they travel?

  1. Use distance = speed × time.
  2. Speed is 12 km/h and time is 2 hours
  3. 12 × 2 = 24

So: The cyclist travels 24 km.

Example 2

A car travels 150 km in 3 hours. What is its average speed?

  1. Use speed = distance divided by time.
  2. Distance is 150 km and time is 3 hours.
  3. 150 divided by 3 = 50

So: The average speed is 50 km/h.

Example 3

A walker travels 12 km at 4 km/h. How long does the walk take?

  1. Use time = distance divided by speed.
  2. Distance is 12 km and speed is 4 km/h
  3. 12 divided by 4 = 3

So: The walk takes 3 hours.