In an article published in journal of medicine, it is reported that in a sample of 123 hip surgeries of a certain type, the average time was 139 minutes with standard deviation 22.6 minutes. find a 95% confidence interval for the mean surgery time.

135 to 143 minutes.

Step-by-step explanation:

Standard deviation (s) = 22.6 minutes

Sample size (n) = 123

Sample average (X) = 139 minutes

The lower and upper bounds of a confidence interval are given by:

Lower bound:

Upper bound:

For a confidence interval of 95%, the z-score value is 1.96.

Therefore, the 95% confidence interval for the mean surgery time is:

Lower bound:

Upper bound:

The 95% confidence interval is 135 to 143 minutes.

c

step-by-step explanation:

it isn't d, because the interquartile range is from 27-57. and the interquartile range is basically half the data, it's pretty obvious.

it isn't b, because like i said earlier, the interquartile range is from 27-57. 57-27 is 30. the real range has to be longer

not a either. although it looks like it, 3/4 of the data is not greater than 27. but if c is wrong than this should be correct

the correct answer is c, because 13 is the point in which the plot starts