There is well of depth 30 m and frog is at bottom of the well. He jumps 3 m in…
2025
There is well of depth 30 m and frog is at bottom of the well. He jumps 3 m in one day and falls back 2 m in the same day. How many days will it take for the frog to come out of the well?
Answer: A. 28 — Solution: Answer: 28 days. Reasoning: Each full day the frog gains 3 m during the day and slips back 2 m at night, so the net gain per full day is 1 m. After…
- A.
28
- B.
27
- C.
30
- D.
29
Attempted by 115 students.
Show answer & explanation
Correct answer: A
Solution:
Answer: 28 days.
Reasoning:
Each full day the frog gains 3 m during the day and slips back 2 m at night, so the net gain per full day is 1 m.
After 27 full days the frog has gained 27 m and is at 27 m depth.
On the 28th day the frog jumps 3 m from 27 m to 30 m and escapes immediately, so it does not slip back that night.
Therefore the frog comes out on day 28.
Common mistake: Counting 30 days by dividing 30 by the 1 m net gain ignores the final day's 3 m jump that lets the frog exit earlier.