Question

Based on interviews with 100 SARS​ patients, researchers found that the mean incubation period was 4.5 days, with a standard deviation of 15.2 days. Based on this​ information, construct a​ 95% confidence interval for the mean incubation period of the SARS virus. Interpret the interval.

1.  The lower bound is ??? days (round to two decimals as needed)

2.  The upper bound is ??? days (round to two decimals as needed)

3.  Interpret the interval and choose the correct answer

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

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

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

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

Answer 1

t critical value at 0.05 level with 99 df = 1.984

95% confidence interval for is

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

4.5 - 1.984 * 15.2 / sqrt(100) < < 4.5 + 1.984 * 15.2 / sqrt(100)

1.48 < < 7.52

Lower bound = 1.48

Upper bound = 7.52

Interpretation -

There is 95% confident that the mean incubation period lies between lower and upper bounds

of confidence interval.