An aeroplane flies along the four sides of a square at speeds of 200, 400, 600 and 800 km/h. Find the average speed of the plane around the field. MCQ with Answer and Explanation
An aeroplane flies along the four sides of a square at speeds of 200, 400, 600 and 800 km/h. Find the average speed of the plane around the field.
A. 432 km/h
B. 400 km/h
C. 500 km/h
D. 384 km/h
Answer: Option D
Solution (By JKSSB Mock Tests)
Let each side of square be 2400 km (LCM of 200, 400, 600, 800). Total distance = 4 * 2400 = 9600 km. Total time = 2400/200 + 2400/400 + 2400/600 + 2400/800 = 12 + 6 + 4 + 3 = 25 hours. Average speed = 9600 / 25 = 384 km/h.
A person walks from his home to his shop at a speed of 5 km/h and arrives 6 minutes early. If he walks at 4 km/h, he arrives 6 minutes late. Find the distance between his home and shop.
Explanation:
When A covers 100m, B covers 85m and C covers 72m. This means in a distance where B covers 85 meters, C covers 72 meters. Therefore, B beats C by 85 - 72 = 13 meters.
No comments yet. Be the first to start the discussion!