A machine produced 20 defective articles in a batch of 400. After overhauling, it produced 10% defectives in a batch of 300. Which test of hypothesis can be applied to the above situation to examine whether the machine has improved?
A. Test of significance of a sample proportion (two-tail test)
B. Test of significance of a sample proportion (one-tail test)
C. Test of significance of difference between two sample proportion (two-tail test)
D. Test of significance of difference between two sample proportion (one-tail test)
Answer:D
A machine produced 20 defective articles in a batch of 400. After overhauling, it produced 10% defectives in a batch of 300. Which test of hypothesis can be applied to the above situation to examine whether the machine has improved?
A. Test of significance of a sample proportion (two-tail test) B. Test of significance of a sample proportion (one-tail test) C. Test of significance of difference between two sample proportion (two-tail test) D. Test of significance of difference between two sample proportion (one-tail test)