If (N(t)=n-6t) and (N(5)=70), what will (N(12)) be?
Answer and explanation
Correct answer: 28
Given \(N(t)=n-6t\). At \(t=5\), \(N(5)=n-30=70\), so \(n=100\). Therefore, \(N(12)=100-6\times12=100-72=28\). Hence, 28 is correct. A value such as 34 can result from an error in subtraction. Exam tip: first find the unknown constant \(n\) from the given value, then substitute the required value of \(t\).
Frequently asked questions
What is the correct answer to this question?
28
Why is this the correct answer?
Given \(N(t)=n-6t\). At \(t=5\), \(N(5)=n-30=70\), so \(n=100\). Therefore, \(N(12)=100-6\times12=100-72=28\). Hence, 28 is correct. A value such as 34 can result from an error in subtraction. Exam tip: first find the unknown constant \(n\) from 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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