Eco 250 Business Statistics Fall 2017 Exam 2 Review 1. [Multiple choice (MC)] Suppose that Apple is conducting a survey of potential iPad users.

I need help with questions 7-10 Also can you show me how you get the answer

7. The average age of the MBA students in a statistics class is 30.7 years old. The ages of five randomly selected students from the class are: 

36 25 25 29 30 

What is the sampling error? 

8. According to a recent study, the average age of "gamers" (those who routinely play video games) is 30 years old. A random sample of 33 gamers had an average age of 32.7 years. Assume that the population standard deviation for the age of gamers is 4.7 years.

1. What is the 90% confidence interval for the mean age of gamers?
2. Would the interval be wider or narrower if you used a 95% or 99% confidence level? 

9. A local store claims that it averages 483 customers per day entering the facility with a standard deviation of 112 customers. To test this claim, you select a random sample of 48 business days.

1. What is the standard error of the sample mean?
2. What is the probability of obtaining a sample mean of 522 or more?
3. What is the probability of obtaining a sample mean within 32 customers of the population mean? 

10. According to the American Veterinary Medical Association, 37% of households own a dog.

1. A random sample of 60 households was selected. a. What is the standard error of the proportion?
2. What is the probability that 18 or fewer of these households own a dog?
3. What is the probability that between 23 and 28 of these households own a dog?