In a city with three high schools, all the ninth graders took a standardized test, with these results: high scool mean score test number of ninth gradeglenwood 79 285central city 94 336lincoln high 72 191the city's pr manager, who never took statistics, claimed the mean score of all ninth graders in the city was 81.7 . of course, that is incorrect. what is the mean score for all ninth graders in the city? use excel. round your answer to one decimal place.

Aresearch study is studying the effects of a new drug for osteoporosis alzheimer's disease (ad) for women above the age of 65 years. a group of individuals with osteoporosis is randomized into two groups. one group is treated conventionally, and the second group is treated with the new medication. assessments are made at 3, 6, 12, 36, and 48 months. the conventionally treated group is assessed for ad using a serum blood test, and the treatment group is assessed for ad using a pet radiotracer that binds to beta-amyloid plaques. in comparing these 2 trial arms, the authors of the study may encounter which type of bias? a. selection bias on the risk of developing b. measurement bias c. confounding bias d. recall bias e. lead-time bias