Question

solve this question fast

Answer 1

For the first half distance: Distance =X  Speed =V1 So time =distance /speed=X/v1.       ...1 For the second distance : Distance=x Speed =v2 So  time =x/v2.            ...2 Average speed = total distance /total time  x+x/(x/v1)+(x/v2) 2x/x(v1+v2)/v1v2 2x(v1v2/v1+v2) 2v1v2/v1+v2   Ans. 2v1v2/v1+v2