Fuel economy A consumer organization has reported test data for 50 car models. We will examine the association between the weight of the car (in thousands of pounds) and the fuel efficiency (in miles per gallon). Here are the scatterplot, summary statistics, and regression analysis: Variable Count Mean StdDev MPG 50 25.0200 4.83394 wt/1000 50 2.88780 0.511656 Dependent variable is: MPG R-squared = 75.6% s = 2.413 with 50 - 2 = 48 df Variable Coefficient SE(Coeff) t-ratio P-value Intercept 48.7393 1.976 24.7 0.0001 Weight -8.21362 0.6738 -12.2 0.0001 a) Is there strong evidence of an association between the weight of a car and its gas mileage? Write an appropriate hypothesis. b) Are the assumptions for regression satisfied? c) Test your hypothesis and state your conclusion.

Components of Statistics Collecting and analyzing data in order to create a reliable sample. ● Population: The units involved in an issue an individual is interested in investigating. Typically, entire populations are too large to measure. ○ Students at the University of Illinois are a population. ● Sample: a smaller set of individual units selected from the investigation.Sampling solves the issue of large numbers, but it will also cause uncertainty. Aspects of the sample do not always correlate with the vast majority. ○ Individuals that are in statistics classes are a sample of the students at the University. ● Statistics: This is where the sample is used. The purpose of statistics is better understand the populati