If (N(t)=n-4t) and (N(5)=35), what will (N(12)) be?
Answer and explanation
Correct answer: 7
Given \(N(t)=n-4t\). Substituting \(t=5\) gives \(N(5)=n-20=35\), so \(n=55\). Now, substituting \(t=12\), \(N(12)=55-4(12)=55-48=7\). Therefore, the correct answer is 7. The value 11 can result from incorrectly handling the decrease of \(4\times 7=28\) from \(t=5\) to \(t=12\). Exam tip: first find the unknown constant \(n\) using the given value, then substitute the required value of \(t\).
Frequently asked questions
What is the correct answer to this question?
7
Why is this the correct answer?
Given \(N(t)=n-4t\). Substituting \(t=5\) gives \(N(5)=n-20=35\), so \(n=55\). Now, substituting \(t=12\), \(N(12)=55-4(12)=55-48=7\). Therefore, the correct answer is 7. The value 11 can result from incorrectly handling the decrease of \(4\times 7=28\) from \(t=5\) to \(t=12\). Exam tip: first find the unknown constant \(n\) using the given value, then substitute the required value of \(t\).
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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