Question

In a theater there are 15 chairs in the first row, each row has 3 more chairs than the previous

row, and there are 17 rows. How many chairs are in the theater? (10 points)

Answer 1

To find the total number of chairs in the theater, you can use the formula for the sum of an arithmetic series. So there are 663 chairs in the theater.

Step-by-step explanation:

To find the total number of chairs in the theater, we can use the formula for the sum of an arithmetic series:

S = (n/2)(a + l)

where S is the sum, n is the number of terms, a is the first term, and l is the last term.
In this case, there are 17 rows and each row has 3 more chairs than the previous row. So the first term, a, is 15 and the last term, l, can be calculated as:

l = a + (n-1)d

where d is the common difference, in this case, 3.

Substituting the values, we get:

l = 15 + (17-1)3 = 15 + 16*3 = 63

Now we can calculate the sum of the series:

S = (17/2)(15 + 63) = 8.5 * 78 = 663

So there are 663 chairs in the theater.

Answer 2

Answer:663

Step-by-step explanation:

The first row is 15,so you have to add three from the first row you and you get 18 and then you keep going and going till you get to the 17th row then you add the numbers together.