(a)We often hear that the cost of looking after our ageing population is rising. "Which", the consumer rights organisation reported that the average monthly cost of living in an assisted-living accommodation in the UK is now 3486 per month.

Assume this cost estimate is based on a sample of 120 facilities and, from past studies, it can be assumed that the population standard deviation is = 650. Develop a 90% confidence interval estimate of the mean monthly rent Develop a 95% confidence interval estimate of the mean monthly rent Develop a 99% confidence interval estimate of the mean monthly rent What happens to the width of the confidence interval as the confidence level is increased? Is it reasonable? Explain.