3. A mail-order business prides itself in its ability to fill customers\' orders

Question

3. A mail-order business prides itself in its ability to fill customers' orders in less than six calendar days, on average. Periodically, the operations manager selects a random sample of customer orders and determines the number of days required to fill the orders. On one occasion when a sample of 39 orders was selected, the average number of days was 6.65 with a population standard deviation of 1.5 days. Apply the p-value and the critical value approaches to test the hypotheses at a significance level =.10.

4. The manufacturer of an over-the-counter heartburn relief mediation claims that it product brings relief in less than 3.5 minutes, on average. To be able to make this claim the manufacturer was required by the FDA to present statistical evidence in support of the claim. The manufacturer reported that for a sample of 50 heartburn sufferers, the mean time to relief was 3.3 minutes and the population standard deviation was 1.1 minutes. Test the hypotheses at a significance level =.05 using the critical value approach.

Explanation / Answer

Solution:

3) t = x-/s/n = (6.65-6.00)/(1.5/40)
= 0.65/0.2372
= 2.7403
Using Excel's TINV option, t0.10 = 1.282
Since 2.7403 > 1.282 reject Ho and conclude that the mail-order business is not achieving its goal.

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