Example 1 Positive Correlation = looks like a line going up to the sky from the left of the screen to the right of the screen Negative Correlation = looks like a line going down to the ground from the left of the screen to the right of the screen None = The points do not form a line at all, they are scattered all over the place!
Example 2 Similar Problem: Use your calculator to find the equation for the line of best fit for the data. Round your answer to two decimal places. Residential Vehicle Miles Traveled per Household by Annual Household Income HouseholdIncome (thousands) 10 15 20 25 35 50 60 75 Miles (thousands) 14.2 15.8 19.3 22.3 25.2 28 28.9 29.6
Example 2 Continued Using your graphing calculator follow the instructions below; Before each problem do this: Press On Press 2nd Press + Press 4: ClrAllLists Press Enter
Example 2 continued Once you have done this your calculator clears all the list information for you! Press STAT Press 1:Edit In L1 put in the Household Income In L2 put in the Miles Press 2nd Press Mode (quit) Press STAT Arrow over to CALC Press 4:LinReg ax + b We get LinReg y= ax + b (a is the slope and b is the y-intercept) y= .24x + 14.17
Example 3 Use the equation for the line of best fit to predict the number of mile traveled per household for an annual household income of 30 thousand dollars. Round your answer to the nearest tenth. Use the equation in Example 2. Use the equation we found in questions #3 and plug in 30 for x. y = .24(30) + 14.17 y = 21.37