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. The central limit theorem B. The law of statistical regularly C. The law of inertia of large numbers D. None of the above

A. Sampling error B. Measurement error C. Coverage error D. Non-response error

A. Both (A) and (R) are true B. (A) is true, but (R) is false C. (A) is false, but (R) is true D. Both (A) and (R) are false

A. 0 B. 1 C. 0.4 D. 0.8