In an office building, a room contains 70 chairs. The number of chairs per row is 4 less than twice the number of rows. Find the number of rows.
A) 14 rows
B) 5 rows
C) 8 rows
D) 7 rows
E) 9 rows

Question

Quizplus · Accepted Answer

The number of chairs per row is given as 4 less than twice the number of rows. Let the number of rows be $r$. Then, the number of chairs per row is $2r - 4$. The total number of chairs is the product of the number of rows and the number of chairs per row, which is $r \times (2r - 4) = 70$. Solving the quadratic equation $2r^2 - 4r - 70 = 0$ gives $r = 7$ as the positive solution that makes sense in this context.

In an Office Building, a Room Contains 70 Chairs