Question

Que: An online retailer ships products from overseas with an advertised delivery date within 10 days. To test whether or not deliveries are made within the advertised time, a random sample of 36 orders is selected from a normal population. The sample mean delivery time is 12 days, and the known population standard deviation is 3 days. Conduct the following test of hypothesis using the 0.01 significance level: H0: µ ≤ 10 H1: µ > 10 (a) Is this a one- or two-tailed test? (b) What is the decision rule? (c) What is the value of the test statistic? (d) What is your decision regarding H0? (e) Determine the p-value and interpret it.

Que: 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? - State the decision rule. - Compute the value of the test statistic. - What is your decision regarding the null hypothesis?

Answer 1

e) the P value for the test statistic is

#by using z table

Since the P value is less than 0.01 we reject the null hypothesis. Therefore we have enough evidence to claim that the the mean delivery time is greater than 10 days.