The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 81.1 for a sample of size 512 and standard deviation 7.5. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 80% confidence level). Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place). < < Answer should be obtained without any preliminary rounding.