Hello there, I am having a hard time with these type of questions, would you mind explaining the answer step by step for me please?

A laboratory scale is known to have a standard deviation of= 0.001 gram in repeated weighings. Scale readings in repeated weighings are Normally distributed, with mean equal to the true weight of the specimen. Three weighings of a specimen on this scale give 3.412, 3.416, and 3.414 grams.

A 95% confidence interval for the true weight of this specimen is

3.4140.00196.3.4140.00065.3.4140.00113.