3. Explain why interval estimates with higher confidence levels are less precise than interval estimates with lower confidence levels. How can you increase the precision of an interval estimate with a high confidence level without sacrificing accuracy? [6 marks]

4.Researchers are testing a vaccine to determine its efficacy. Altogether, 10,000 people were recruited for the study ranging in age from 18 to 65 across various genders. If you were conducting this study, what type of experimental design would you use and why? [6 marks]