Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 30.3 for a sample of size 483 and standard deviation 7.9.

Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 90% 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).

< μμ <

Answer should be obtained without any preliminary rounding.

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Answer 1

Since , the population standard deviation is unknown

df=degrees of freedom=n-1=483-1=482

The critical value is ,

; The Excel function is , =TINV(0.1,482)

The 90% confidence interval estimate is ,

a) Therefore , the estimated lower a typical patient's systolic blood pressure is 29.7

b) The tri-linear inequality is