If (A(t)=90-4t) and (B(t)=30+2t), when will (A(t)) be (12) more than (B(t))?
Answer and explanation
Correct answer: \(t=8\)
“12 more” means \(A(t)-B(t)=12\). Therefore, \((90-4t)-(30+2t)=12\), so \(60-6t=12\). Hence, \(6t=48\) and \(t=8\). At \(t=10\), the two values become equal, so it is a close but incorrect option. Exam tip: In “more than” questions, first write the difference between the two quantities.
Frequently asked questions
What is the correct answer to this question?
\(t=8\)
Why is this the correct answer?
“12 more” means \(A(t)-B(t)=12\). Therefore, \((90-4t)-(30+2t)=12\), so \(60-6t=12\). Hence, \(6t=48\) and \(t=8\). At \(t=10\), the two values become equal, so it is a close but incorrect option. Exam tip: In “more than” questions, first write the difference between the two quantities.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Linear growth and decay.
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