As an engineer working for a electrical power company you need to design an experiment to determine a 95% condence interval for the mean daily power usage for homes in Salt Lake City. Measuring the daily power usage of every single home is not practical, therefore you need to choose a sample. What size does your sample need to be to ensure that the con dence interval for is not larger than 5 kWh? Or in other words, what is the minimum sample size that can be used to be 95% con dent that the error between the sample mean x and the population mean will not exceed 5 kWh? Assume that the standard deviation for the population distribution of power usage is known to be = 50kWh.