A manufacturer produces a commodity where the length of the commodity has approximately normal distribution with a mean of 9.9 inches and standard deviation of 2.7 inches. If a sample of 48 items are chosen at random, what is the probability the sample's mean length is greater than 9.1 inches

Astudy claims that the mean age of online dating service users is 40 years. some researchers think this is not accurate and want to show that the mean age is not 40 years. identify the null hypothesis, h0, and the alternative hypothesis, ha, in terms of the parameter μ. select the correct answer below: h0: μ≥40; ha: μ< 40 h0: μ≤40; ha: μ> 40 h0: μ≠40; ha: μ=40 h0: μ=40; ha: μ≠40