Answer Happy

business statistics
3. According to the GTEC, the mean costs (fees, room, and board rates) for a four-year public university in the Ghana was e15640 for the 2013-2014 academic year. Assume the costs follow a normal distribution with or=2000. If a random sample of 60 costs for four-year public university was taken that year. a) what is the expected value of the sample mean? b) what is the standard deviation of X2 c) what is the probability that the sample mean is over e17000? d) what is the probability that the sample mean is within e1000 of the population mean? 4. (1) The kilowatt/hour (kWh) generated by a solar system of 12 panels from (12-1 p.m.), during the summer months, has a normal distribution with mean 2.25 and a standard deviation of 0.5. If 10 solar systems of this kind are randomly sampled, find a) the probability that the sample average is 3 kWh or more. b) the probability that the sample average is between 2.09 and 2.41 kWh. (ii) State in which of these cases it is more reasonable to assume that X follows a normal distribution and explain why or why not a) sample of size 2 comes from a population with normal distribution (known variance). b) sample of size 10 comes from a population with normal distribution (unknown variance). 5. a. Two of your employees are conducting statistical analysis. Each one is working with a random sample of 30. The first employee took the sample from a population with a symmetric distribution. The second employee took the sample from a highly skewed distribution. Both based their conclusions on the sample mean following approximately a normal distribution. For which of the two employees do you think the normal assumption is more appropriate? b. A solar power company must determine the sample size to infer on the mean utility bill of residents. From previous studies, it was established that the population standard deviation is 25 kilowatts/hour (kWh). They would like a margin of error of 2kWh and a confidence level of 95%. What is the sample size needed?