A person rides bicycle on four different ways to reach the destination. Determine the average speed during this whole journey.

Correct option is B

Formula Used:
​$$\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}}$$​​
Solution:
Total Distance = 20 km+ 15 km + 10 km + 24 km = 69 km
Time taken in way A = $$\frac{20 \, \text{km}}{5 \, \text{km/h}} = 4 \, \text{hours}$$​​
Time taken in way B = $$\frac{15 \, \text{km}}{3 \, \text{km/h}} = 5 \, \text{hours}$$​​
Time taken in way C = $$\frac{10 \, \text{km}}{2 \, \text{km/h}} = 5 \, \text{hours}$$​​
Time taken in way D = $$\frac{24 \, \text{km}}{4 \, \text{km/h}} = 6 \, \text{hours}$$​​
Total Time = 4 hours + 5 hours+ 5 hours + 6 hours = 20 hours
Average Speed = $$\frac{69 \, }{20}$$​ = 3.45 km/h
Therefore, the average speed during the whole journey is 3.45 km/h.