A diagnostic test for drug use among Olympic athletes based on a blood sample was thought to be excellent. Among drug users, 98% had a positive test. Among nondrug users, 95% had a negative test. Suppose that 1% of the athletes are, indeed, drug users. What proportion of the athletes tested would have a positive test? Of those athletes whose test is positive, what proportion are really drug users?

1) a researcher is studying a population of bats in which 16% of the population has a certain trait. the researcher wants sampling distribution with a standard deviation that is less than 2%. which sample sizes could the researcher use? select all that apply : a)n=200 b) n=300 c) n=400 d) n=500 2) from a normal distribution population, a simple random sample of size 38 is taken. the mean of the sample is 82 and the standard deviation of the sample is 4. what is the 90% confidence interval for the population mean? round to the nearest tenth ( [1], 83.1)