A bolt fabrication machine makes bolts with a target length of mu =15.125 millimeters. The machine has some variability, so the standard deviation of the length is sigma =0.175 millimeter. The machine operator inspects a random sample of 12 bolts each hour for quality control purposes and records the sample mean diameter, x. Assuming the process is working properly, what are the mean and standard deviation of the sampling distribution of ?

μₓ = 15.125 and Σ ₓ=0.175
μₓ =12 and Σ ₓ=0.175
μₓ =12 and Σ ₓ=0.0505
μₓ =15.125 Σ ₓ=3.46
μₓ =15.125 Σ ₓ=0.0505