stat workbook

 open the excel sheet and instruction are on the first page. Please show all work and detail so, for example someone with limited knowledge in Statistics can understand the answer.

Q.

The management of a bank in the Caribbean was concerned about the potential loss that might occur in the event of a hurricane.  The bank estimated that the loss from one of these storms could be as much as $100 million including losses due to interrupted service and customer relations.  One project the bank is considering is the installation of an emergency power generator at its operations headquarters.  The cost of the emergency generator is $800,000, and if it is installed no losses from this type of storm will be incurred.  However, if the generator is not installed, there is a 10% chance that a power outage will occur during the next year.  If there is an outage there is a 5% probability that the resulting losses will be very large or approximately $80 million in lost earnings.  Alternatively, it is estimated that there is a 95% probability of only slight losses of around $1 million. Using decision tree analysis, determined whether the bank should install the new power generator.

Q-3a.  A stationery store wants to estimate the mean retail value of greeting cards purchased by its customers when they visit the store.  A random sample of 15 customers  indicates a mean amount of $2.55 with a standard deviation of $0.44 per customer per visit.  Assuming a  normal distribution, construct a 95% confidence interval estimate of the mean retail value of greeting cards purchased by its customers.

Q-3b.  A paper manufacturer has a production process that operates continuously throughout an entire production shift.  The paper is expected to have a mean length of 11 inches, and the standard deviation of the length is 0.02 inches.  At periodic intervals, a sample is selected to determine whether the mean paper length is still equal to 11 inches or whether something has gone wrong in the production process to change the length of the paper produced.  You select a random sample of 100 sheets, and the mean paper length is 10.998 inches.  Construct a 95% confidence interval estimate for the population mean paper length.

Q-3c.  A survey of 705 workers  asked how much they used the Internet at work.  423 said they used it within limits, and 183 said that they did not use the Internet at work.  Construct a 95% confidence interval estimate for the proportion of all workers who use the Internet within limits.

Q-3d.  You are the designer for your company's web site.  You have data to indicate that the mean download time for the homepage is 7 seconds and that the standard deviation of download time is 2.0 seconds.  If we assume that the download times are normally distributed, what percent of users will wait between 5 and 10 seconds for the homepage to download?