Rope Puzzle
At the equator the radius of the earth is 6,378 km, so its circumference is almost exactly 40,000 km.
Imagine we had a long rope which went around the equator, this would of course be 40,000 km long.
If we now placed 1 metre sticks vertically all the way around and lay the rope on top of these sticks (i.e. the rope would be 1m higher all the way around) how much extra rope would we require?
Solution (Previous Puzzle):
1. d)
2. c)
3. a)
4. b)
Looking at the questions, only Q2 has an answer that doesn't reference itself directly. For example Q1 asks about c) as an answer, but its answer c) is Q1.
So it's easiest to look at Q2 first.
Q2's answer can't be b) (as this would be an immediate contradiction), so Q4's answer can't be a), so Q2's answer can't be a).
Q2 can therefore be either c) or d).
If Q2's answer was d), then Q1's answer would be a), so Q3's answer would be c), so Q4's answer would be d), so Q1's answer would be b). However this now contradicts itself, so Q2's answer can't be d).
Therefore Q2's answer must be c). Making Q3's answer a), making Q1's answer d), confirming Q2's answer is c). Leaving Q4's answer as b).
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