ADM2303 Assignment Assignment one- Solution ADM2303 spring 2015 100% Satisfaction Guaranteed!

Assignment one - part II
Total points : 50
Part I of the assignment :
• Must be done via MySytatlab
• Due-date: Monday, May 25, 11:59 P.M.
Part II of the assignment :
• Please don't forget to complete your signed statement of Academic Integrity within the
body of your solution
• Submit a PDF of your type-written (i.e., not handwritten) solution (recall that a submission
cannot be marked unless it is in PDF format).
• Submit your assignment via blackboard learn by due-date Monday, May 25, 11:59 P.M.
• Use MiniTab or Excel (or any other statistical tool ) if you need to. However you should
cut and paste your result and sufficient explanation.
• Make sure to provide details calculations and steps of how you arrived at your answer
when appropriate . Providing only the software output is not acceptable.
Question one (10 points)
Here are advertised house power rating and expected gas mileage, in mile per gallon, for several
2010 vehicles. (www.kbb.com)
a) Which one of these variables is explanatory and which one is response variable ? (1 point)
The horsepower is explanatory and gas mileage is response variable.
b) Using an appropriate tool make a scatterplot for these data. (2 points)
The scatterplot of gas mileage versus horsepower is shown below:
Car hp mpg
Audi A4 211 30
BMW 3 series 230 28
Buick LaCrosse 182 30
Chevy Cobalt 155 37
Chevy Suburban 320 21
Ford Expedition 310 20
GMC Yukon 320 21
Honda Civic 140 34
Honda Accord 177 31
Hyundai Elantra 138 35
Lexus IS 350 306 25
Lincoln Navigator 310 20
Mazda Tribute 171 28
Toyota Camry 169 33
Volkswagen Beetle 150 28
!
c) Describe the direction, form, and strength of the association. (2 points)
There is a strong, negative, straight association between horsepower and mileage of the selected
vehicles. There don’t appear to be any outliers. All of the cars seem to fit the same pattern. Cars
with more horsepower tend to have lower mileage. [NOTE: The plot seems to be missing two of
the 15 models, but in fact there are two pairs of identical points].
d) Find the correlation between horsepower and miles per gallon. (2 points)
Since the relationship is linear, with no outliers, correlation is an appropriate measure of
strength. The correlation between horsepower and mileage of the selected vehicles is –0.909.
e) Write a few sentences telling what the plot says about fuel economy. (1 point)
There is a strong linear relationship in the negative direction between horsepower and highway
gas mileage. Lower fuel efficiency is associated with higher horsepower.
f) Convert the mileage to litres per 100 km (=235.2 ÷ mpg) and repeat part b) to e). Did the
correlation change ? which scale for fuel consumption do you prefer and why ? (2 points