An assembly has x rows, with x+30 chairs in each row. If there are 2275 chairs in total, how many rows are there?
Answer and explanation
Correct answer: 35
The total number of chairs gives the equation x(x+30)=2275, or x^2+30x-2275=0. Factoring, (x-35)(x+65)=0, so x=35 or x=-65. Since the number of rows cannot be negative, the valid answer is 35. Exam tip: In arrangement word problems, reject any negative root and retain the positive value that fits the context.
Frequently asked questions
What is the correct answer to this question?
35
Why is this the correct answer?
The total number of chairs gives the equation x(x+30)=2275, or x^2+30x-2275=0. Factoring, (x-35)(x+65)=0, so x=35 or x=-65. Since the number of rows cannot be negative, the valid answer is 35. Exam tip: In arrangement word problems, reject any negative root and retain the positive value that fits the context.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Quadratic Equations. Topic: Word Problems and Applications.
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