The National Institute of Standards and Technology (NIST) supplies "standard materials" whose physical properties are supposed to be known. For example, you can buy from NIST a copper sample whose melting point is certified to be 1084.80 C. Of course, no measurement is exactly correct. NIST knows the variability of its measurements very well, so it is quite realistic to assume that the population of all measurements of the same sample has the Normal distribution with mean equal to the true melting point and standard deviation = 0.25 'C. Six measurements on the same copper sample, which is supposed to have melting point 1084.80 C, are provided. 1084.55 Copper Melting Point (C) 1084.89 1085.02 1084.79 1084.69 1084.86 NIST wants to give the buyer of this copper sample a 90% confidence interval for its true melting point. What is this interval? Click to download the data in your preferred format. CSV Excel JMP Mac-Text Minitab14-18 Minitab18+ PC-Text R SPSS TI Crunchlt! SOLVE: Calculate a 90% confidence interval. Use software or statistical tables for your calculations. Give your answers to four decimal places. (If you are using Crunchlt, change the default precision for confidence interval and mean to "8". This will give answers to four decimal places.) lower bound: 1084.8 C Incorrect upper bound: 1085.2 Incorrect C