there are sixty students in a class of which boys and girls sit in pairs then half of the girls are left, find no of girls ? a=20 b=30 c=40 d=50 if anyone can so plz

The police chief wants to know if the city’s african americans feel that the police are doing a good job. identify the management problem (i.e dependent variable) and identify the independent variable.

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

Find the value of x. also give me an explanation so i can complete it to other questions as well, : )