Chicken Delight claims that 86 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 80 orders revealed that 65 were delivered within the promised time. At the .10 significance level, can we conclude that less than 86 percent of the orders are delivered in less than 10 minutes?

Question

(a) What is the decision rule? (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)

Reject Ho if z <

(b) Compute the value of the test statistic. (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)


Value of the test statistic

Answer 1

You can probably use a one-sample proportional test for your data. (Test sample proportion = 65/80 or .8125) Find the appropriate table for your critical value at .10 level of significance for a one-tailed test. Compare the test statistic you calculate to the critical value from the table. If the test statistic exceeds the critical value, reject the null. If the test statistic does not exceed the critical value, do not reject the null. You can draw your conclusions from there.

Answer 2

Chicken Delight claims that 88 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 60 orders revealed that 50 were delivered within the promised time. At the .05 significance level, can we conclude that less than 88 percent of the orders are delivered in less than 10 minutes?