Based on interivews with 84 SARS patients researchers found

Based on interivews with 84 SARS patients, researchers found that the mean incubation period was 4.3 days, with a standard deviation of 14.8 days. Based on this information, construct a 95% confidence interval for the mean incubation period of the SARS virus.

the lower bound is ____ days. (round answer two decimal places as needed.)

the upper bound is ____ days  (round answer two decimal places as needed.)

Interpret the interval.(Select the correct answer below)

a. there is a 95% confidence that the mean incubation period lies between the lower and upper bounds of the interval.

b. there is a 95% confidence that the mean incubation period is less than the lower bound of the interval.

c. there is a 95% probbability that the mean incubation period lies between the lower and upper bounds of the interval.

d. there is a 95% confidence that the mean incubation period is greater than the upper bound of the interval

Solution

Given a=1-0.95= 0.05, Z(0.025) = 1.96 (from standard normal table)

So the lower bound is

xbar - Z*s/vn =4.3 - 1.96*14.8/sqrt(84) =1.13

So the upper bound is

xbar + Z*s/vn =4.3 + 1.96*14.8/sqrt(84) =7.47

----------------------------------------------------------------------------------------------------

a. there is a 95% confidence that the mean incubation period lies between the lower and upper bounds of the interval.