Question: Leaving my computer on "standby" when not using it saves electricity. My null hypothesis is that I put my computer on standby before I went on vacation last week, but I'm not sure. When I do put it into power-saving mode, it uses a mean of 3.11 kWh in a day, std. dev. of 0.54. How much power would it have to consume per day over those 7 days for me to believe I'd forgotten to use standby (alpha = 0.01)?