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. 384 km/h
C. 500 km/h
D. 400 km/h
Answer: Option B
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.
Two cars A and B leave an intersection simultaneously. A travels North at 45 km/h and B travels East at 60 km/h. Find the direct distance between them after 1 hour.
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