Question

Example-10. In a flower bed, there are 27 rose plants in the first row, 29in the second, 18 in
the third, and so on. There are 5 rose plants in the last row. How many rows are there in the
flower bed?​

Answer 1

Answer:

If you meant 23 flowers in the first row, 21 in the second and so on, then the answer is 10 rows.

Step-by-step explanation:

In 1st row ---> 23 plants

In 2nd row ---> 21 plants and so on...

This is an AP where:

a = first term = 23

d = common difference = 21 - 23 => -2

n = no. of rows = ?

a = last term = 5

Now, we know that an = a + (n - 1)d

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

=> 5 = 23 - 2n + 2

=> 5 = 25 - 2n

=> 2n = 25 - 5 => 20

∴ n = no. of rows = 20/2 => 10 rows