If a marathon runner runs a distance of 5 km (kilometers) in 45 minutes. What is his speed?

Given parameters:

Distance  = 5km

Time taken = 45 minutes

Unknown:

Speed  = ?

Solution:

Speed is a physical quantity.

It is given as;

   Speed  =

Since the unknown is speed;

     convert the time given to hours;

         60min  = 1hr

         45min =   =

So, speed  =   = 5 x  

                        = km/hr

b.

developed countries have tended to improve the environment, while developing countries have tended to damage it.