A sample of 81 observations from a normal population
A sample of 81 observations from a normal population
1. A sample of 81 observations from a normal population is taken with a standard deviation of 5. The sample mean is 40 Determine the confidence interval of 95% for the population mean.
2. MacBurger restaurant chain claims that the waiting time of customers is 3 minutes with a population standard distribution of 1 minute. The quality control department found a sample of 50 clients in Warren Road MacBurger that the average waiting time was 2.75 minutes. With the significance level of 0.05 can you conclude that the mean waiting time is less than 3 minutes?
3. Each month, the National Association of Purchasing Managers publishes the NAPM index. One of the questions posed in the survey of purchasing agents is: Do you think the economy is expanding? Last month, the 300 responses, 160 were affirmative. This month, 170 of the 290 responses indicated that the economy was expanding. With a significance level of 0.05. Can we conclude that a larger proportion of agents feel the economy is expanding this month?
4. A doctor who specializes in weight management recommends three different diets. As part of an experiment, 15 randomly selected patients and then assigns 5 of them to each diet. After three weeks the following weight reduction observed in pounds. With a significance level of 0.05 can you conclude that there is a difference in the average amount of weight loss among the three diets?
