A battery decreases by the model (B(h)=120-10h) percent. When will the battery be (50%)?
Answer and explanation
Correct answer: \(h=7\)
Set \(B(h)=50\) because the battery level is required to be 50%. Thus, \(120-10h=50\), so \(10h=70\) and \(h=7\). At \(h=6\), the battery level would be 60%, so that option is not correct. Exam tip: In linear decay questions, equate the model to the required value first and then solve for the variable.
Frequently asked questions
What is the correct answer to this question?
\(h=7\)
Why is this the correct answer?
Set \(B(h)=50\) because the battery level is required to be 50%. Thus, \(120-10h=50\), so \(10h=70\) and \(h=7\). At \(h=6\), the battery level would be 60%, so that option is not correct. Exam tip: In linear decay questions, equate the model to the required value first and then solve for the variable.
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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