There are 10 stepping stones numbered 1 to 10 as shown at the side . A fly…
2024
There are 10 stepping stones numbered 1 to 10 as shown at the side . A fly jumps from the first stone as follows . Every minute it jumps to the 4th stone from where it started thaat is from 1st it would go to 5th and from 5th it would go to the 9th and from 9th it would go to 3rd etc . Where would the fly be at the 60th minute if it starts at 1 ?
- A.
1
- B.
2
- C.
3
- D.
4
Attempted by 461 students.
Show answer & explanation
Correct answer: A
Answer: 1
Explanation:
Each minute the fly moves 4 stones forward. Starting from stone 1 the positions are: 1, 5, 9, 3, 7, and then back to 1.
This sequence has length 5 (it returns to 1 after 5 moves), so the positions repeat every 5 minutes.
Since 60 = 5 × 12, after 60 minutes the fly completes 12 full cycles and is back at the starting stone, which is stone 1.
You can also use modular arithmetic: position after n jumps = 1 + 4n (mod 10). For n = 60, 4×60 = 240 ≡ 0 (mod 10), so the position is 1.
Therefore the fly will be on stone 1 at the 60th minute.