Question

A cat climbs a 21-meter pole. In the first minute it climbs 3 meters and in the second minute it descends one meter. In how many minutes will the cat reach the top of the pole?

• A. 21 minutes
• B. 18 minutes
• C. 19 minutes
• D. 20 minutes

Hint:

Consider the cycle of climbing and descending, and handle the final step separately.

Answer 1

The Correct Option is C

Step 1: Calculate the net progress per 2-minute cycle.
In the first minute, the cat climbs 3 meters, and in the second minute, it descends 1 meter, effectively climbing 2 meters every 2 minutes. 
Step 2: Determine how many cycles are required.
The total height of the pole is 21 meters. In each 2-minute cycle, the cat climbs 2 meters. So, to reach 19 meters, the cat needs: \[ \frac{19}{2} = 9.5 \quad \text{(round up to 10 cycles)}. \] Step 3: Account for the final climb.
In the 19th minute, the cat climbs 3 meters to reach the top, and thus, the total time is 19 minutes. Thus, the correct answer is: \[ \boxed{19 \, \text{minutes}}. \]