The manager of Tea for Us has been ordering stock based on the assumption that 40% of her customers prefer black teas. The following hypotheses are given:
H₀: p = 0.40
H₁: p ≠ 0.40
She sampled 120 of her customers and found that only 30% of those preferred black teas. At the 0.05 significance level, can the null hypothesis be rejected?
a. State the decision rule.
b. Compute the value of the test statistic.
c. What is your decision regarding the null hypothesis?