A train covers half the distance of its journey with a speed 20 m s-1 and the other half with a speed of 40 m s-1. The average speed of the train during the whole journey isA. 25 m s-1B. 27 m s-1C. 30 m s-1D. 32 m s-1E. 35 m s-1SolutionShow solution >>The answer is B.Let the total distance travelled by the train be d and the time taken for it to complete the first half and second half of the