In a senior college, 25% of the Year 11 students and 40% of the Year 12 students would
prefer not to wear school uniform. This particular college has 320 Year 11 students and
280 Year 12 students. Find the probability that a randomly chosen student is in Year 11
and is in favour of wearing school uniform. What is the overall percentage of students
who are in favour of wearing school uniform?

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