A person walks alonga rectangular field, whose dimensions are 6 km long and 3 km wide. For the first 1 hour, he walks at a speed of 2 km/hr. After 1 hour, he increases his speed to 4 km/hr. Next 1 hour, his speed is decreased to 2 km/hr. For the next 1 hour, he increases his speed to 4 km/hr. Find his average speed (in km/hr).
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 3.
Speeds per hour:
1st hour – 2 km
2nd hour – 4 km
3rd hour – 2 km
4th hour – 4 km
Total distance = 2 + 4 + 2 + 4 = 12 km
Total time = 4 hours
Average speed = Total distance ÷ Total time = 12 ÷ 4 = 3 km/hr