Questions: A rectangular auditorium seats 1316 people. The number of seats in each row exceeds the number of rows by 19. Find the number of seats in each row. Answer

A rectangular auditorium seats 1316 people. The number of seats in each row exceeds the number of rows by 19. Find the number of seats in each row.

Answer
Transcript text: A rectangular auditorium seats 1316 people. The number of seats in each row exceeds the number of rows by 19. Find the number of seats in each row. Answer
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Solution

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Solution Steps

To solve this problem, we need to set up a system of equations based on the given information. Let \( r \) be the number of rows and \( s \) be the number of seats per row. We know that the total number of seats is 1316, so \( r \times s = 1316 \). Additionally, the number of seats in each row exceeds the number of rows by 19, so \( s = r + 19 \). We can substitute the second equation into the first to solve for \( r \), and then use that value to find \( s \).

Step 1: Define Variables

Let \( r \) be the number of rows in the auditorium. According to the problem, the number of seats in each row exceeds the number of rows by 19. Therefore, the number of seats in each row can be expressed as \( r + 19 \).

Step 2: Set Up the Equation

The total number of seats in the auditorium is given as 1316. Therefore, we can set up the equation based on the total number of seats:

\[ r \times (r + 19) = 1316 \]

Step 3: Expand and Rearrange the Equation

Expand the equation:

\[ r^2 + 19r = 1316 \]

Rearrange it into a standard quadratic equation form:

\[ r^2 + 19r - 1316 = 0 \]

Step 4: Solve the Quadratic Equation

To solve the quadratic equation \( r^2 + 19r - 1316 = 0 \), we can use the quadratic formula:

\[ r = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

where \( a = 1 \), \( b = 19 \), and \( c = -1316 \).

Calculate the discriminant:

\[ b^2 - 4ac = 19^2 - 4 \times 1 \times (-1316) = 361 + 5264 = 5625 \]

Calculate the square root of the discriminant:

\[ \sqrt{5625} = 75 \]

Substitute back into the quadratic formula:

\[ r = \frac{-19 \pm 75}{2} \]

Calculate the two possible solutions for \( r \):

\[ r = \frac{-19 + 75}{2} = \frac{56}{2} = 28 \]

\[ r = \frac{-19 - 75}{2} = \frac{-94}{2} = -47 \]

Since the number of rows cannot be negative, we have \( r = 28 \).

Step 5: Calculate the Number of Seats in Each Row

The number of seats in each row is \( r + 19 \):

\[ r + 19 = 28 + 19 = 47 \]

Final Answer

The number of seats in each row is \(\boxed{47}\).

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