A study on annual salaries of accountants in 2021 with over 5 years of experience was conducted. Below are the annual salaries (in EUR) of 14 randomly selected accountants in the study. 42,300 42,350 42,450 42,700 42,850 42,850 43,220 43,565 43,600 43,650 43,900 44,520 44,620 44,650 Question 9: Assume that the standard deviation of salaries in 2020 is the same as that of 2021. Estimate the average salary in 2021 using the given sample above at a 95% confidence level. Question 10: The assumption made in Question 9 is perhaps unreasonable. Estimate the average salary in 2021 again with 95% confidence, assuming that the standard deviation of salaries in 2021 is different from that of 2020. Question 11: Estimate the proportion of the salaries in 2021 that are less than 43,000 EUR using the sample provided above at a 95% confidence level. Question 12: Estimate the variance of the salaries using the sample provided above at a 95% confidence level. Question 13: Based on the result in Question 12 above, is it reasonable to believe that the standard deviation of the salaries in 2021 is the same as that of 2020? A data analyst is about to carry out a study on the ann