Multiple choice

The distance between two stations P and Q is 982 Km. A train covers journey from P to Q at 90 km/hr and returns back to P with uniform speed of 49 km/hr. Find the average speed of train during the whole journey

  1. 71 km/hr approx.

  2. 63 km/hr approx.

  3. 75 km/hr approx.

  4. 69 km/hr approx.
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B Correct answer
Explanation

Average speed for a round trip is (2 * v1 * v2) / (v1 + v2). Here v1 = 90, v2 = 49. Average speed = (2 * 90 * 49) / (90 + 49) = 8820 / 139 = 63.45 km/hr, which is approximately 63 km/hr.

AI explanation

The time taken to travel from P to Q is 982 divided by 90, and the return time is 982 divided by 49. Using the average speed formula for equal distances, the speed equals 2 multiplied by 90 multiplied by 49 divided by the sum of 90 and 49. This calculates to 8820 divided by 139, which approximates to 63 km/hr.

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