A car travels four consecutive distances of 2 km each at speeds of 10 km/hr, 20 km/hr, 30 km/hr, and 40 km/hr, respectively. What is the average speed of the car (in km/hr) over this total distance?

Correct option is C

Given:

The car travels four equal distances of 2 km each at different speeds:

1st 2 km at 10 km/h

2nd 2 km at 20 km/h

3rd 2 km at 30 km/h

4th 2 km at 40 km/h

Formula Used:

Average Speed = ​​$$\frac{\text{Total Distance}}{\text{total time}}$$​​

Solution:

Average Speed = $$\frac{8}{\frac{2}{10} + \frac{2}{20} + \frac{2}{30} + \frac{2}{40}}$$​​

​$$=\frac{8}{ \frac{1}{5} + \frac{1}{10} + \frac{1}{15} + \frac{1}{20}} \\ \ \\= \frac{8}{\frac{12 + 6 + 4 + 3}{60}} \\ \ \\= \frac{8}{\frac{25}{60}} \\ \ \\= 8 \times \frac{60}{25} \\ \ \\= \frac{480}{25}$$​​

= 19.2 km/hr