A biker travels from point A to Point C in a straight line at 15m/s. Along the way he stops at point B to rest. Neglecting resting time, whats the average speed from point B to Point C?
1. The average speed between A and B is 10m/s
2. From B to C took him 20s
The question is not worded properly. It should be 'he travels from A to C at an average speed of 15 m/s'. Nevertheless,
Statement 1 is not sufficient alone. Until and unless we have the ratio of time taken from A to B and time taken from B to C or the ratio of distance AB and distance BC, we cannot find his average speed from B to C.
e.g. Average speed from B to C could be 20 if he traveled the two legs of the journey in equal time or could be 30 if he traveled from A to B in 3 times the time it took him to travel from B to C and so on. (Refer theory of weighted averages for further clarification)
Statement 2 is not sufficient alone. We just know the time taken from B to C. We do not know the distance BC and hence we cannot say what his average speed was.
Taking both together, we still do not have the ratio of their time taken or ratio of the distance AB:BC. Hence they are together not sufficient.
Answer is (E).
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