If (M(t)=42+4t) and (N(t)=96-5t), when will (M(t)) be (9) more than (N(t))?
Answer and explanation
Correct answer: \(t=7\)
“9 more” means \(M(t)=N(t)+9\). Thus, \(42+4t=96-5t+9\), or \(42+4t=105-5t\). Hence \(9t=63\), so \(t=7\). At \(t=6\), the difference is only \(0\), so it is a close but incorrect option. Exam tip: For “more than” questions, equate the larger quantity to the smaller quantity plus the stated difference.
Frequently asked questions
What is the correct answer to this question?
\(t=7\)
Why is this the correct answer?
“9 more” means \(M(t)=N(t)+9\). Thus, \(42+4t=96-5t+9\), or \(42+4t=105-5t\). Hence \(9t=63\), so \(t=7\). At \(t=6\), the difference is only \(0\), so it is a close but incorrect option. Exam tip: For “more than” questions, equate the larger quantity to the smaller quantity plus the stated difference.
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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