Going downstream a boat covers 50 miles at a speed of 60 mph. While returning it takes 1 hour 15 minutes to cover the same distance. What is the average speed for the whole journey?

Correct option is B

Formula Used:​
$$\text{Average Speed} = \frac{ \text {Total Distance}} {\text{Total Time}}$$​​

Solution:

Time to cover 50 miles with the speed of 60 mph = 50/60 × 60 = 50 min
Total time = 50 min + 75 min = 125 min
Total distance = 50 + 50 = 100 miles
As we know,
Average speed = Total distance/Total time
Average speed = 100/125 × 60
Average speed = 48 mph