A textile fibre manufacturer is investigating a new drapery yarn, which the company claims has a mean thread elongation of 12 ππππ and a standard deviation of ππ=1.5 ππππ. The company wishes to test π»π»0: ππ=12 πππ π»π»ππ:ππ<12 suing a random sample of four specimens. If the critical region is defined as ππτ΄€<11.5 ππππ, what is the probability of type I error?