Question 1075890: Updated questions with added information:
A specific study found that the average number of doctor visits per year for people over 55 is 8 with a standard deviation of 2. Assume that the variable is normally distributed.
1. Suppose a random sample of 15 people over 55 is selected. What is the probability that the sample mean is above 9?
2. Suppose a random sample of 100 people over 55 is selected. What is the probability that the sample mean will be below 7?
A study found that citizens spend on average $1950 per year on groceries with a standard deviation of $100. Assume that the variable is normally distributed.
3. Find the probability that a sample of 500 citizens will have a mean greater than $2000.
I also need help with these.
Use the chi-squared distribution to test the hypothesis.
4) A restaurant owner wants to see if the business is good enough for him to purchase a restaurant. He asks the present owner for a breakdown of how many customers that come in for lunch each day and the results are as follows: Monday - 20, Tuesday - 30, Wednesday - 25, Thursday - 40 and Friday - 55. The prospective owner observes the restaurant and finds the following number of customers coming for lunch each day: Monday- 30, Tuesday - 15, Wednesday- 7, Thursday 40, and Friday - 33. At a 95% confidence level determine whether the present owner reported the correct number of customers for lunch each day.
find the critical value.
5. There is an annual hot dog eating contest in Plattsburg, MS and the average number of hot dogs eaten by one person is 36 with a standard deviation of 6. Find the critical value for a person who can eat more than 2 deviations above the mean.
6. A company found that 27 out of 150 of its products were defective after retraining its employees. If the company normally has a 40% defective product rate, find the critical value to determine if retraining the employees helped to minimize the number of defective products.
7. A teacher gives 200 students a study guide for a test and the average score was 90 with a standard deviation of 6. She did not give the other 200 students a study guide and their average score was 70 with a standard deviation of 8. Find the critical value to determine whether or not the study guide helped students to increase their test score.
Answer by ikleyn(52756)   (Show Source):
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