Vitamin B6 is one of the vitamins in a multiple-vitamin pill manufactures by a pharmaceutical company. The pills are produced with a mean of 50 milligrams of vitamin B6 per pill. The company believes that there is a deterioration of 1 milligrams per month, so after 3 months they expect that µ = 47. A consumer group suspects that the mean is actually much less, and decide to conduct a test.
Based on a random sample of size 24 from a normal distribution, the data gives X(bar) = 45.6615 and s2 = 26.7855.
a. Construct a 99% confident interval for the standard deviation of the amount of vitamin B6 per pill.
b. Test µ = 47 versus µ < 47 at the 1% significance level. Clearly state the conclusion.