Every Month for a Period of Many Years, a Homeowner

Short Answer

Every month for a period of many years, a homeowner kept track of several variables related to natural gas and electricity usage in his house, before and after he added a new room to the house. The following scatterplots show the average daily natural gas usage vs. mean temperature for the month and average daily electricity usage vs. mean temperature for the month, respectively.
a. Which utility's usage (natural gas or electricity) appears to be more temperature dependent for this homeowner? Explain how you can tell from the scatterplots.
b. Do the scatterplots provide any reason to believe that natural gas or electricity usage (or both) are higher after the extra room is added? Explain how you can tell.