Logical Reasoning

Sequence & Series

Medium

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:

✅ Correct Option: 2

The flower bed has:

Row 1: 23 plants
Row 2: 21 plants
Row 3: 19 plants
Last row: 5 plants

Each row has 2 fewer plants than the previous row (23 → 21 → 19).

This is an arithmetic progression with common difference $d = -2$ .

For an arithmetic progression, the nth term formula is:

$a_n = a + (n-1) \times d$

Where:

$a_n = 5$ (plants in last row)
$a = 23$ (plants in first row)
$d = -2$ (common difference)
$n = ?$ (number of rows)

Substituting the values:

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

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

$5 = 23 - 2n + 2$

$5 = 25 - 2n$

$2n = 25 - 5$

$2n = 20$

$n = 10$

Therefore, the number of rows in the flower bed is 10.

2026: 14 May Shift 2

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2025: 26 May Shift 1

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2026: 19 May Shift 2

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2026: 25 May Shift 2

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2025: 24 May Shift 2

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2026: 29 May Shift 1

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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:

Solution

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