Question

QUESTION PART A: The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 66.8 for a sample of size 638 and standard deviation 5.7.

Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 95% 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).

QUESTION PART B: If n=23, ¯x=30x¯=30, and s=10, find the margin of error at a 80% confidence level

Give your answer to two decimal places.

Answer 1

A)

sample mean 'x̄=	66.80
sample size    n=	638.00
std deviation σ=	5.700
std errror ='σx=σ/√n=	0.2257

for 95 % CI value of z=		1.960
margin of error E=z*std error =		0.44
lower bound=sample mean-E=		66.358
Upper bound=sample mean+E=		67.242

from above: 95% confidence level of population mean : = 66.4 < μ < 67.2

B)

sample mean 'x̄=	30.000
sample size   n=	23.00
sample std deviation s=	10.000
std error 'sx=s/√n=	2.0851

for 80% CI; and 22 df, value of t=		1.321
margin of error E=t*std error    =		2.75