The pulse rates of 162 randomly selected adult males vary from a low of 42 bpm to a high of 102 bpm. find the minimum sample size required to estimate the mean pulse rate of adult males. assume that we want 90% confidence that the sample mean is within 2 bpm of the population mean. complete parts (a) through (c) below.
a. find the sample size using the range rule of thumb to estimate σ
b. assume that σ = 11.5 bpm, based on the value s= 11.5 bpm from the sample of 152 male pulse rates
c. compare the results from parts (a) and (b). which result is likely to be better?
the result from part (a) is larger than the result from part (b). the result from part (a) is likely to be better because it uses a better estimate of σ.

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