Compute Total Distance

$\text{Total Distance} = 5 + 5 = 10\text{ km}$

Compute Total Time Taken

• Morning time $t_1 = 1\text{ h}$ • Evening time $t_2 = 1\text{ h} + 15\text{ min} = 1 + \frac{1}{4} = \frac{5}{4}\text{ h}\text{Total Time } T = 1 + \frac{5}{4} = \frac{9}{4}\text{ hours}$

Calculate Average Speed

$\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{10}{\frac{9}{4}} = \frac{40}{9} = 4 \frac{4}{9}\text{ km/h}$

$\text{Average speed} = 4 4/9 km/h$