Standard deviation 

part 1). A sample of size 103 from a population having standard deviation ? = 9 produced a mean of 45. The 99% confidence interval for the population mean (rounded to two decimal places) is:The lower limit is The upper limit isPart 2). The mean federal income tax paid last year by a random sample of 36 persons selected from a city was $4244. Suppose the standard deviation of tax paid in this city is ? = $721. The 95% confidence interval for the population mean (rounded to two decimal places) is:The lower limit is $The upper limit is $Part 3). A random sample of 90 customers, who visited a department store, spent an average of $71 at this store. Suppose the standard deviation of expenditures at this store is ? = $18. The 98% confidence interval for the population mean (rounded to two decimal places) is:The lower limit is $The upper limit is $Part 4). The mean IQ score of a sample of 52 students selected from a high school is 89. Suppose the standard deviation of IQ’s at this school is ? = 6.5. The 99% confidence interval for the population mean (rounded to two decimal places) is:The lower limit is The upper limit is