The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction

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The effectiveness of a blood-pressure drug is being
investigated. An experimenter finds that, on average, the reduction
in systolic blood pressure is 67.9 for a sample of size 921 and
standard deviation 5.9. Estimate how much the drug will lower a
typical patient's systolic blood pressure (using a 99% 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). < μ < Answer should be
obtained without any preliminary rounding.