The electric cooperative needs to know the mean household usage of electricity by its non commercial customers in kEH per day. They need estimate to...

The electric cooperative needs to know the mean household usage of electricity by its non commercial customers in kEH per day. They need estimate to have a maximum error of 0.14. A previous study found that for an average family the standard deviation is 2.5 and the mean is 17 per day. If they are using a 99% level ofConfidence how large of a sample is required to estimate the mean usage of electricity