(a) A study is to be carried out that requires 99% confidence of estimating the proportion of students who study over 3 hours per day to within :l:0.105. How large the sample size of students should be for such estimation? The critical value is [correct to 4 decimal places]. According to the formula [select one below] On = (z/e)2/4 05: :l: za/J OR = P(1 - 10)(Z/e)2 On : (arr/e)2 05: :l: its/ OP i fopll Pl the required sample size is at least [correct to 2 decimal places]. Therefore, the required sample size is (b) A researcher plans to estimate the mean score of statistics exam of a population of students to within :14 marks at 95% confidence level. The standard deviation of the examination score of the population is 22.71 . What is the sample size required? The critical value is [correct to 4 decimal places]. According to the formula [select one below] 05% :l: ts/ On = P(1 Pllz/e)2 On = (za/e)2 01mm On: (z/e)2/4 Oi :l: zU/ the required sample size is at least [correct to 2 decimal places]. Therefore, the required sample size is