Question

Andy took a bus and then walked from his home to downtown.
For the first 16 hour, the bus drove at an average speed of 15
km/h. For the next 0.4 hours, he walked at an average speed
of 4.5 km/h. What was the average speed for the whole
journey?

Answer 1

Given :

Speed of bus for first 16 hours is , u = 15 km/h .

Distance he walked for next 0.4 hour is , v = 4.5 km/h .

To Find :

The average speed for the whole  journey.

Solution :

Average speed is given by :

$v_{avg}=\dfrac{u_1t_1+u_2t_2}{t_1+t_2}\\\\v_{avg}=\dfrac{15\times 16 + 4.5\times 0.4}{16+0.4}\\\\v_{avg}=14.74\ km/h$

Therefore , the average speed of the journey is 14.74 km/h .

Hence , this is the required solution .