Question

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. The number of rows in the flower bed are......

• A. $11$
• B. $41$
• C. $10$
• D. $9$

Answer 1

The correct option is C $10$

Here, the number of plants in consecutive rows form an AP, where a=23, d=-2.
Last row, $t_n=5$
$t_n=a+(n-1)d$
$5=23+(n-1)(-2)$
n=10.