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2. Hand et a1. provide several data sets pertaining to experiments on insulating houses in Great Britain. One such study is described as follows: \"In the mid-19705 an experiment on insulation was carried out on an estate of housing in public ownership in Whitburn, Scotland. The control houses and ats were insulated to the usual standard at that time: no insulation in the wall cavities, and 25 mm of insulation in the roof. The experimental houses had cavity insulation, and 100m of roof insulation. The houses were heated by electricity. These data give the total electricity consumption in kWh for 3e year gm June 1975 for the 15 two-bedroom houses which were constantly occupied throughout at perio .\" (a) Use R to conduct an appropriate test of the null hypothesis that the extra house insulation had no effect on average energy consumption. A one-sided alternative hypothesis is appropriate here; explain why and state the null and alternative hypotheses precisely. Use a 5% level of signicance and use the p-value to draw appropriate conclusions. (b) Estimate the energy saved with a 95% condence interval. [Note: We will stick to two-sided condence intervals in this course]