At Ajax Spring Water, a half-liter bottle of soft drink is supposed to contain a mean of 520 ml. The filling process follows a normal distribution with a known process standard deviation of 4 ml. (a) The normal distribution should be used for the sample mean because:.
1. the sample population has a large mean.
2. the population distribution is known to be normal.
3. the population standard deviation is known.
4. the standard deviation is very small.
(b) Set up hypotheses and a two-tailed decision rule for the correct mean using the 5 percent level of significance.
The hypothesis for a two-tailed decision is:.
1.. H0: μ ≠520, H1: μ = 520, reject if z < −1.96 or z > 1.96
2. H0: μ ≠520, H1: μ = 520, reject if z > 1.96 or z < −1.96
3. H0: μ = 520, H1: μ ≠ 520, reject if z > 1.96 or z < −1.96
4. H0: μ =520, H1: μ ≠ 520, reject if z > −1.96 or z < 1.96