I need help with these Statistics problem

5. Researchers are interested in the relationship between developing dementia and the expression of a certain gene. A gene is expressed if it is mutated, or its coded information is converted into certain proteins. The researchers take a random sample of 200 people, all aged 50 or above. For each person selected the researchers determine: . whether or not the person is showing signs of dementia . whether or not the gene is expressed age sex diet exercise habits 95419.\":er a] Is this an example of an experimental study or an observational study? Explain. b) What is the response variate in this study? c] What type of variate is the response variate? d] What type of model could be used to model the response variate? e) Is a subject's sex an example of an explanatory variate? [Yes or No) 4. {Show your work / justify your answer in each part) Suppose that the weights of ofce workers at StatCo are Normally distributed with mean equal to 75 and a variance of 81. *** Use the standard Normal probability table in this question. Please give answers to 3 decimal places. *** a) What is the interquartile range of the distribution of the weights of the StatCo office workers? b] Suppose 9 ofce workers are chosen at random. Let Yi = weight of the il worker, i =1,2,...,9. The distribution of l7 = g 13:1 Yi is GI , I. [Fill in the blanks with numerical values; justify these values in the space below also). C) Is the distribution of l7 in part b) exact or approximate? Explain. d) Now suppose that the capacity and load limit of an ofce-building elevator is 9 persons or 720 kg. What is the probability that average weight of 9 randomly selected office workers exceeds 80 kg? Note: This would also represent the probability that the load limit of the elevator was exceeded