Arithmetic Progression

Step 1: Understanding the Concept:
The number of plants in the rows forms an arithmetic progression (AP), as the difference between consecutive terms is constant.
Step 2: Key Formula or Approach:
The formula for the nth term of an AP is:

where is the nth term, is the first term, n is the number of terms, and d is the common difference.
We need to find 'n' (the number of rows).
Step 3: Detailed Explanation:
The sequence of the number of plants is 23, 21, 19, ... , 5.
The first term, .
The last term, .
The common difference, .
Now, substitute these values into the nth term formula:

Subtract 23 from both sides:


Divide both sides by -2:


Add 1 to both sides:

Step 4: Final Answer:
There are 10 rows in the flower bed.