Discuss one threat to internal validity as it specifically relates to this research 17) scenario. ANSWER Use this information to answer the following questions: Age at onset of dementia was determined in the general population to be u = 70 and 0 =7.0. Based on the data above, what is the z score for someone being diagnosed with dementia at age 65 (can round to two decimal places)? What percentage of 18) people might start to show signs of dementia before this age ( DO NOT ROUND). I Score = Work: ANSWER % =