QUESTION 8 A random sample of 400 households was 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 377.744 KWh. The standard deviation of the usage was 64 KWh. Find the upper confidence limit of the 99% confidence interval for the mean usage in the last quarter. O a. 384 KWh O b. 380 KWh O C. 382 KWh O d. 386 KWh O e. 388 KWh