Can you explain with step by step workings? on a paper?

QUESTION 3 The management of a hospital wants to know the average number of days required for in-paent treatment of teenage patients. A random sample of 500 teenage patients produced a mean and standard deviation of 5.4 and 3.1 days respectively. Determine a 95% condence interval for the mean length of stay for the teenage patient population. Assume population is normally distributed. QUES'HON 4 The mean montth expenditure on electricity per household is determined by selecting a random sample of 36 households. The sample mean is $68. with a sample standard deviation of $171 What is a 95% condence interval for the mean monthly expenditure on electricity per household? QUESON 5 An investment advisor believes that the return on stocks is approximately normally distributed. A sample of 24 interest-sensitive stocks were selected. It was found that their mean yearty return and standard deviation is 10.946913 and 3.313%. Find a 90% condence interval for the mean yearty return on stocks. QUESTION 5 One of the objectives of a large medical study was to estimate the mean physician fee for cataract removal. For 25 randomly selected cases the mean fee was found to be $1550 witt'l a standard deviation of $125