Question

A company manufacturing computer chips finds that 8% of all chips manufactured are defective. In an effort to decrease the percentage of defective chips, management decides to provide additional training to those employees hired within the last year. After training was implemented, a sample of 450 chips revealed only 27 defects. A hypothesis test is performed to determine if the additional training was effective in lowering the defect rate. Which of the following statement is true about this hypothesis test?

A. It is a two tailed test about a proportion.
B. It is a one tailed test about a mean.
C. It is a one tailed test about a proportion.
D. It is a two tailed test about a mean.
E. None of the above.

Answer 1

A. It is a two tailed test about a proportion

Explanation:

We are given;

Population proportion; p= 8% = 0.08

Sample size; n = 450

Defective ones in the sample = 27

Sample proportion; p^ = 27/450 = 0.06

Let's define the hypotheses.

Null Hypothesis; H0: p = 0.08

Alternative hypothesis;Ha: p ≠ 0.08

≠ is used for the alternative hypothesis because we can't really ascertain if the training was going to make things worse.

Thus, this is a two tailed hypothesis test about a proportion.