7. The Frog
A frog is at the bottom of a 30 meter well. Each day he summons enough energy for one 3 meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?
Note: Assume after the first leap that his hind legs are exactly three meters up the well. His hind legs must clear the well for him to escape.
Submitted by GmdAquaman · Added 1 January 2007
Hint: Try to think the problem through for a five meter well. Now what is the solution for the 30 meter well?
Solution:
28
Each day he makes it up another meter, and then on the twenty eighth day he can leap three meters and climb out.
Comments (12)
It should be 28 days as on the morning of the 27th, the frog has only jumped 26 meters.
The answer seems to be wrong. It says the answer is 28 but the explanation says 27.
On the problem 7. The Frog, why is the answer 28 and not 27?
He exits exactly 27 days after making his first jump, on his 28th jump. The explanation gives the correct answer, but the numeric answer is wrong.
The Frog puzzle has a numerical error in the answer. He exits exactly 27 days after making his first jump, on his 28th jump.
The burglar would take longer to escape the building due to the presence of banks.
The answer I put was 28 days, but it was marked incorrect. I checked the answer and I was right. Please do fix.
The cook's action of removing two white beans doesn't make sense. If he did, there would still be 150 black beans left, meaning the remaining bean would be a white bean among the black ones.
The fisherman would indeed travel downstream with the flow, which contradicts the initial premise. However, the answer remains two hours.
The frog needs to rest for a day after a leap. It will take 28 days for his hind legs to clear the ledge.
In puzzle 7, the frog, there are two different solutions provided. The correct answer should be 27, not 28.
Assuming day 1 is the first day he takes a jump, it will be day 28 that he escapes from the well. However, the total amount of time elapsed is 27 days since he made his first jump.
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