If Sally walked 1/2 kilometer in 1/4 hour, how fast, in kilometers per hour, was she walking?

Solution:

Speed is the rate at which an object moves. The object could be a lorry, car airplane, or even for that matter a human being.

Speed is mathematically defined as Distance / Time

Distance could be expressed in units such as mile, km, meters while time as we all know could be in seconds, minutes, hours, or even days if the case be.

Therefore in the problem statement, Sally walks 1/2 kilometer in 1/4 hour. The speed in kilometers per hour would become:

Speed = Distance/Time = (1/2)/(1/4) = 2 km/hour

The same speed can be expressed in minutes per second by multiplying speed in km/hour by 1000/3600 = 5/18 which results in:

2 × 5/18 = 5/9 metres per second = 0.55 metres per second

If Sally walked 1/2 kilometer in 1/4 hour, how fast, in kilometers per hour, was she walking?

Summary:

If Sally walked 1/2 kilometer in 1/4 hour, then the speed in kilometers per hour 2 km/hour.