1. A salesperson created a 99% confidence interval of (253.78, 463.61) megabytes per month to estimate the average capacity usage of an iPhone.What is the value of the width of this confidence interval?Please give your answer correctly rounded to two decimal places and do NOT include units in your answer.
2. An electricity provider wants to estimate the mean time it takes for customers to get an electrical fault resolved. The provider took a random sample of 36 customers who had recently reported an electrical fault and found a mean time of 4 hours.Assume the population standard deviation is 0.73 hours. What is the value of the margin of error for a 95% confidence interval?Please give your answer correctly rounded to two decimal places and do NOT give units.
3. The production manager at a textile mill, believes that a new machine, producing cloth, is not workingaccording to the company's specifications.The company requires that the cloth should have a mean breaking strength of 57 Kg.A sample of 63 pieces of cloth reveals a sample mean breaking strength of 40.8 Kg and a standard deviation of 2.1 Kg.If the manager wants to make a hypothesis test to her belief, what value of the mean would be used in the null and the alternative hypotheses?