On a particular day, 3 friends, Anisha, Tanisha and Minisha start riding their mopeds from the same place at the same time in the morning and return back together to the same place at the same time in the evening. On reading their vehicle speedometers, the three friends realise that they had driven their mopeds at average speeds of 40kmph, 45 kmph and 35 kmph respectively. Find their average speed for the entire journey.

Since the three friends start and return together, the time taken for the entire journey is identical for all of them. The average speed for the entire group is simply the arithmetic mean of their individual speeds. Adding their speeds gives 40 + 45 + 35 = 120 kmph, and dividing by 3 yields an average speed of 40 kmph.

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