NIMCET 2024 — Reasoning PYQ
NIMCET | Reasoning | 2024A cat climbs a 21- meter pole. In the first minute it climbs 3 meter and in the second minute it descends one meter. In how minutes the cat would reach the top of the pole ?
Choose the correct answer:
- A.
18 min
- B.
21 min
- C.
19 min
(Correct Answer) - D.
20 min
19 min
Explanation
This is a classic arithmetic puzzle involving alternating progress. The most crucial trick to remember is that once the cat reaches the top of the pole, it does not slip back down.
Step 1: Set aside the final jump
Total height of the pole = 21 meters
Height climbed in the final positive attempt = 3 meters
To avoid calculating slips after the goal has been achieved, subtract the final minute's climb from the total height:
Remaining height to analyze=21−3=18 meters
Step 2: Find the net progress in a single cycle
Let us calculate how much net height the cat covers during its standard repeating cycle:
1st minute: Cat climbs +3 meters
2nd minute: Cat slips down −1 meter
Net distance covered=3−1=2 meters
Total time taken for this progress=1+1=2 minutes
So, the net progress is 2 meters every 2 minutes.
Step 3: Calculate time required to reach the safe height (18 meters)
Since the cat climbs a net height of 2 meters in a 2 minute block, we calculate the number of cycles required to reach at least 18 meters:
Number of cycles=2 meters/cycle18 meters=9 cycles
Now, multiply the cycles by the time length of each cycle:
Time taken for 9 cycles=9×2 minutes=18 minutes
At exactly 18 minutes, the cat has securely reached a height of 18 meters.
Step 4: Add the final step
In the next minute (the 19th minute), it is the cat's turn to make a positive climb again.
Current height = 18 meters
Distance covered in the next 1 minute = +3 meters
Final Height=18+3=21 meters
The cat reaches the exact top (21 meters) at the end of this minute, so it will not slip back.
Total time required=18 minutes+1 minute=19 minutes
Correct Answer:
The correct option is (C) 19 min.
