please find the test statistics also

A random sample of 225 lab practicals was selected from the past 5 years and the number of students absent from each one recorded. The average number of absences was found to be 11.6 and the standard deviation over the past 5 years was known to be 4.1 absences. (Note: This is the population standard deviation.) (i) Estimate the mean number of absences per practical (u) over the past 5 year with (a) 90% confidence, (b) 95% confidence, (c) 99% confidence. (ii) If it was known that the mean number of absences of students over a long time is 12.0, test whether the mean number of student absences from the past 5 years is different at the (a) 5% level of significance. (b) 1% level of significance