Question

Football Stadium The corner section of a football stadium has 15 seats in the first row and 40 rows in all. Each successive row contains two additional seats. How many seats are in this section?

Short answer

There are total of 2160 seats in this section .

Step-by-step solution

Given Information 

The corner section of a football stadium has 15 seats in the first row and 40 rows in all. Each successive row contains two additional seats

a=15

n=40

d=2

Total seats

To find out total seats we use sum formula

$$\begin{gathered} S_n=\frac{n}{2}\left(2a_1+(n-1)d\right) \\ {S}_n=\frac{40}{2}\left(2\left(15\right)+(40-1)\left(2\right)\right) \\ {S}_{40}=20\left(30+39\left(2\right)\right) \\ {S}_{40}=2160 \end{gathered}$$

There are total of 2160 seats in this section