A medical variable is believed to be norrnail}r distributed. Knowing the mean tells whether a certain medicine is effective. The mean p: is uninsiwn and needs to be estimated. It's time consuming to do experiments and get an observation for this variable. A medical student plans to spend a month to get a random sample of size 4: {rhxhxm L}. Denote the standard deviation of the distribution by rt, the sample mean by I", the sample valianne by SE =im=11 - Ida. What's the standard error of I\"? Wbat's the mean square error of 3' for estimating In? What's the distribution onfX' Mfrs? 1'I:'I.I"llat's the disbibrrdion of 26?; p] ('5'? What's the distribution ofi; irFfE}