QUESTION 7 A random sample of 100 household as selected as part of a study on electricity usage, and the number of kilowatt-hours (kWh) used last quarter was recorded for each household in the sample. The average usage was found to be 376 944 kWh. The standard deviation of the usage was 36 kWh Find the upper confidence limit of the 95% confidence interval for the mean usage in the last quarter. a 384 kWh b.382 kWh OC 388 kWh Od 380 kWh 0.386 kWh