Answer:
1) The mean calculated for this case is 
2) 
3) 
4) B. An interval estimate gives us a sense of the accuracy of the point estimate whereas a point estimate alone does not.
Because with the confidence interval we know the confidence level of the interval, and the limits for the parameter at some significance level.
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Part 1
In order to calculate the mean and the sample deviation we can use the following formulas:
(a)
(b)
The mean calculated for this case is
The sample deviation calculated 
population mean (variable of interest)
n=6 represent the sample size
Part 2
The confidence interval for the mean is given by the following formula:
(1)
So if we have the margin of error 5.4mm we can find the lowr limit like this:
Part 3
Part 4
B. An interval estimate gives us a sense of the accuracy of the point estimate whereas a point estimate alone does not.
Because with the confidence interval we know the confidence level of the interval, and the limits for the parameter at some significance level.
