Question

Refer to the accompanying​ TI-83/84 Plus calculator display of a​ 95% confidence interval. The sample display results from using a simple random sample of the amounts of tar​ (in milligrams) in cigarettes that are all king​ size, nonfiltered,​ nonmenthol, and​ non-light. Express the confidence interval in the format of x overbarplus or minusE. ZInterval ​(19.356​,21.764​) x overbarequals20.56 nequals20 The confidence interval is nothingplus or minus nothing.

Answer 1

Solution :

  = (Lower confidence interval + Upper confidence interval ) / 2

Sample mean = = (19.356 + 21.764) / 2 = 20.56

Margin of error = E = Upper confidence interval -   = 21.764 - 20.56 = 1.204

E = 20.56 1.204