A car travels from a place X to place Y at an average speed of v km/hr from y to X at an average speed of 2v km/hr, again from X to y at an average speed of 3v km/hr and again from y to x at an average speed of 4v km/hr. Then the average speed of the car for the entire journey
is less than v km/hr
lies between v and 2v km/hr
lies between 2v and 3v km/hr
lies between 3v and 4v km/hr
Average Speed = Total distance ÷ Total time. Let us assume that distance between X and Y be ‘a’. Then, total distance = a + a + a + a = 4a. And total time = Distance/Speed = a/v + a/2v + a/3v +a/4v = 25a/12v So, average speed for the entire journey = 4a/ (25a/12v) = 48v/25 = 1 .92v. So the correct option is (b) i.e. between v and 2v.
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