The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 41.2 for a sample of size 20 and standard deviation 15.7. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 95% confidence level). Assume the data is from a normally distributed population. Enter your answer as a tri-linear inequality accurate to three decimal places.