An aeroplane flies along the sides of an equilateral triangle with speed of…
2025
An aeroplane flies along the sides of an equilateral triangle with speed of 300 km/hr, 200 km/hr, 240 km/hr. The average speed of the plane while flying around the triangle is:
- A.
250 km/hr
- B.
290 km/hr
- C.
340 km/hr
- D.
240 km/hr
Attempted by 8 students.
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Correct answer: D
Step-by-Step Solution
When an object travels equal distances at different speeds, the average speed is calculated using the harmonic mean.
Identify the variables:
The aeroplane travels along the three sides of an equilateral triangle, meaning the distance for each segment is equal.
Speeds: x = 300 km/hr, y = 200 km/hr, z = 240 km/hr.
Apply the average speed formula for three equal distances:
Average Speed = (3 * x * y * z) / (xy + yz + zx)
Perform the calculation:
Numerator = 3 * 300 * 200 * 240 = 43,200,000
Denominator = (300 * 200) + (200 * 240) + (300 * 240)
Denominator = 60,000 + 48,000 + 72,000 = 180,000
Average Speed = 43,200,000 / 180,000 = 240 km/hr.