statistics, mth

Question

the effectiveness of a blood-pressure drug is being investigated. an experimenter finds that, on average , the reduction in systolic blood pressure is 33.5 for a sample of size 25 and standard deviation 18.3 , estimate how much the drug will lower a typical patient's systolic blood pressure ( using a 90% confidence level )

Answer 1

To compute confidence interval for population mean:

sample mean +/- t-critical value * standard deviation/square root(sample size)

t-critical value for 90% confidence at 24 (sample size - 1) degrees of freedom = 1.711