In the linear rule (S(t)=120-8t), what is the rate of change per unit?
Answer and explanation
Correct answer: -8
In a linear rule, the coefficient of t gives the rate of change per unit. In S(t)=120-8t, the coefficient of t is -8, so S decreases by 8 when t increases by 1. Here, 120 is the initial value, not the rate; 8 gives only the magnitude of the decrease, so the negative sign is essential. Exam tip: In the form y=a+bt, the rate of change is b.
Frequently asked questions
What is the correct answer to this question?
-8
Why is this the correct answer?
In a linear rule, the coefficient of t gives the rate of change per unit. In S(t)=120-8t, the coefficient of t is -8, so S decreases by 8 when t increases by 1. Here, 120 is the initial value, not the rate; 8 gives only the magnitude of the decrease, so the negative sign is essential. Exam tip: In the form y=a+bt, the rate of change is b.
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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