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Question
A frog has fallen 10 feet down a well. Every hour it makes a hop up the well
which takes it three feet upwards but it then slides back down two feet.
How long does it take the frog to extricate itself from the well ? Answer
The frog starts at 10 feet down the well ( -10 ), it hops up 3 feet ( -7 ),
we start our timer, it then slides down 2 feet ( -9 ).
After 1 hour it hops up 3 feet ( -6 ) and then slides down 2 feet ( -8 ).
After 2 hours it hops up 3 feet ( -5 ) and then slides down 2 feet ( -7 ).
After 3 hours it hops up 3 feet ( -4 ) and then slides down 2 feet ( -6 ).
After 4 hours it hops up 3 feet ( -3 ) and then slides down 2 feet ( -5 ).
After 5 hours it hops up 3 feet ( -2 ) and then slides down 2 feet ( -4 ).
After 6 hours it hops up 3 feet ( -1 ) and then slides down 2 feet ( -3 ).
After 7 hours it hops up 3 feet ( 0 ) and hops away to freedom. 7 hours
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