Final answer:
To change the confidence interval to contain zero, we need to adjust the mean of the sample by finding an acceptable value that would make it equal to the median.
Step-by-step explanation:
To change the confidence interval to contain zero, we need to adjust the mean of the sample. Since the mean is a lot bigger than the median, we can decrease the mean by finding an acceptable value that would make it equal to the median. Let's say the median is M.
We can find the acceptable value A by calculating A = 2M - mean. By subtracting this value from each data point in the sample, we can create a new sample with a mean equal to the median and thereby change the confidence interval to contain zero.
By doing this, we are essentially shifting the entire data set so that the mean and the median are equal.