Question

Based on interviews with

8484

SARS​ patients, researchers found that the mean incubation period was

55

​days, with a standard deviation of

15.415.4

days. Based on this​ information, construct a​ 95% confidence interval for the mean incubation period of the SARS virus. Interpret the interval.

The lower bound is

nothing

days.​ (Round to two decimal places as​ needed.) The upper bound is

nothing

days. ​(Round to two decimal places as​ needed.)

Interpret the interval. Choose the correct answer below.

A.

There is a​ 95% probability that the mean incubation period lies between the lower and upper bounds of the interval.

B.

There is​ 95% confidence that the mean incubation period is less than the lower bound of the interval.

C.

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

D.

There is​ 95% confidence that the mean incubation period is greater than the upper bound of the interval.

Answer 1

t critical value at 0.05 level with 83 df = 1.989

95% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

55 - 1.989 * 15.4 / sqrt(84) < < 55 + 1.989 * 15.4 / sqrt(84)

51.66 < < 58.34

Lower bound = 51.66

Upper bound = 58.34

Interpretation -

There is​ 95% confidence that the mean incubation period lies between the lower and upper bounds of the interval