If y = 160 - 12x, what will be the total decrease in y from x = 2 to x = 7?
Answer and explanation
Correct answer: 60
The equation y = 160 - 12x is linear, and the coefficient of x is -12. This means y decreases by 12 units whenever x increases by 1 unit. From x = 2 to x = 7, the increase in x is 7 - 2 = 5. Therefore, the total decrease is 12 × 5 = 60 units. The starting value and final value also confirm this: y(2) = 136 and y(7) = 76, so 136 - 76 = 60. Hence option B is correct; the other values result from using an incorrect interval or rate.
Frequently asked questions
What is the correct answer to this question?
60
Why is this the correct answer?
The equation y = 160 - 12x is linear, and the coefficient of x is -12. This means y decreases by 12 units whenever x increases by 1 unit. From x = 2 to x = 7, the increase in x is 7 - 2 = 5. Therefore, the total decrease is 12 × 5 = 60 units. The starting value and final value also confirm this: y(2) = 136 and y(7) = 76, so 136 - 76 = 60. Hence option B is correct; the other values result from using an incorrect interval or rate.
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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