Question

Task   1
Suppose producer claims that the mean strength of a wire is 25 psi and   standard deviation is 4psi.Production of wire is normally distributed. A sample of   20 observations is taken from the process and mean is calculated 20psi.α =0.05 level of significance.

a) Apply suitable test to verify producer’s claim.
Task 2
Suppose a company claims that content of   pollution in water emitted by manufacturing process is not more than 100ppb, and standard deviation 5. Sample of size 25 values is taken from polluted water its average content is 95ppb
Verify   claim applying suitable statistical knowledge. Where α =0.05(level of significance).
Task   3
A manufacturer introduced new technique to develop his   product.
The population average production is 100 pieces, standard   deviation   5 pieces.
Production is normally distributed with sample mean 105 and sample size 25
Manufacturer wants to test whether his production improved after application of technique or
not. Level   of significance α=0.01.

Answer 1