In a flower bed there are 23 rose plants in the first row, 21 in the second, 19 in the third and so on. There are 5 rose plants in the last row. Then the number of rows in the flower bed is:

10

The correct answer is Option (2) → 10

Given:

• First row: a = 23
• Second row: 21
• Third row: 19
• Last row: l = 5
• Common difference: d = 21 - 23 = -2

We need number of rows n.

AP formula for nth term

$l = a + (n-1)d$

$5 = 23 + (n-1)(-2)$

$5 = 23 - 2(n-1)$

$5 = 23 - 2n + 2$

$5 = 25 - 2n$

$2n = 25 - 5 = 20$

$n = 10$