A stadium seats people in rows so that row 1 seats 20 people and each higher row seats 4 more.
The stadium fills exactly 2340 people across all rows.
How many rows are there?

Question

A stadium seats people in rows so that row 1 seats 20 people and each higher row seats 4 more. The stadium fills exactly 2340 people across all rows. How many rows are there?

Accepted Answer

30. a = 20, d = 4. Sn = n/2[40+(n-1)4] = n/2(36+4n) = n(18+2n) = 2340, so 2n^2 + 18n - 2340 = 0, n^2 + 9n - 1170 = 0. Factor: (n-30)(n+39) = 0, so n = 30 rows.

A stadium seats people in rows so that row 1 seats 20 people and each higher row seats 4 more.
The stadium fills exactly 2340 people across all rows.
How many rows are there?

Step-by-Step Solution

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More Class 10 AP Word Problems practice

A stadium seats people in rows so that row 1 seats 20 people and each higher row seats 4 more.The stadium fills exactly 2340 people across all rows.How many rows are there?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 AP Word Problems practice

A stadium seats people in rows so that row 1 seats 20 people and each higher row seats 4 more.
The stadium fills exactly 2340 people across all rows.
How many rows are there?