Question

# How does the fuel consumption of a car change as its speed increases? Here are data...

How does the fuel consumption of a car change as its speed increases? Here are data for a British Ford Escort. Speed is measured in kilometers per hour, and fuel consumption is measured in liters of gasoline used per 100 kilometers traveled. Speed Fuel 10 21.00 20 13.00 30 10.00 40 8.00 50 7.00 60 5.90 70 6.30 80 6.95 Speed Fuel 90 7.57 100 8.27 110 9.03 120 9.87 130 10.79 140 11.77 150 12.83

(a) Make a scatterplot. (Do this on paper. Your instructor may ask you to turn in this work.) What is the explanatory variable? The explanatory variable is: Correct: Your answer is correct.

(b) Describe the form of the relationship. It is not linear. Explain why the form of the relationship makes sense. The relationship is curved--high in the middle, lower at the extremes because low fuel efficiency is actually good (it means that we use more fuel to travel 100 km), this makes sense: moderate speeds yield the worst performance. The relationship is curved--low in the middle, higher at the extremes because high fuel efficiency is actually bad (it means that we use more fuel to travel 100 km), this makes sense: moderate speeds yield the worst performance. The relationship is curved--low in the middle, higher at the extremes because high fuel efficiency is actually good (it means that we use less fuel to travel 100 km), this makes sense: moderate speeds yield the best performance. Correct: Your answer is correct.

(c) Does it make sense to describe the variables as either positively associated or negatively associated? Correct: Your answer is correct.

Why? This answer has not been graded yet. THIS IS THE PART I NEED

(d) Is the relationship reasonably strong or quite weak? reasonably strong quite weak Correct: Your answer is correct.

All I need is part C and D and only the Why? and Explain your answer part?

(c) The variables are negatively associated.
The correlation coefficient between the two variables has come out to be -0.17. A negative number of this statistic indicates that there is negative association between them.

(d) The relationship between the variables is quite weak.
The correlation coefficient between the two variables has come out to be -0.17. This number is very close to 0 (that is, no association), such a low, negative correlation value indicates that there is a weak, negative relation between them.