Question

In a theater there are 12 chairs in the first row, each row has 2 more chairs than the previous row, and there are 10 rows. How many chairs are there in the theate

Answer 1

Answer:

  210

Step-by-step explanation:

The first term of the sequence, a1, is 12. The common difference, d, is 2. The number of terms is n = 10. The sum is given by the formula ...

  Sn = (2a1 +d(n-1))(n/2)

Filling in the numbers, this is ...

  S10 = (2·12 +2(10-1))(10/2) = (24+18)(5) = 210

There are 210 chairs in the theatre.

Answer 2

This theatre contains a total of 210 chairs.

Each row has 2 more chairs than the last row and the first row has 12 chairs.

The rows are therefore:

1st row ⇒ 12

2nd row ⇒ 14

3rd row ⇒ 16

4th row ⇒ 18

5th row ⇒ 20

6th row ⇒ 22

7th row  ⇒ 24

8th row ⇒ 26

9th row ⇒ 28

10th row ⇒ 30

The total number of chairs in the hall is therefore:

= 12 + 14 + 16 + 18 + 20 + 22 + 24 + 26 + 28 + 30

= 210 chairs

In conclusion, there are 210 chairs in this theatre.

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