A. Solve the following problem.

1. A random sample of size 100 has a standard deviation of 25 and a sample mean of 33. What is the margin of error for a 90% confidence level? What is the confidence interval of the statement? Solution:

2. The average price of 250 cellphones is Php. 16,300 with a sample standard deviation of Php. 750. A Construct a 99% confidence interval of the true average price of the cellphones. B. Compute for the length of the confidence interval Solution: B. Solve the following problem.

1. A nurse at Lucena United Medical Center is interested in estimating the birth weight of infants. How large a sample must be if she desires to be 98% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of birth weights is known to be 6 ounces. Solution:

2. A 99% confidence interval has to be created to estimate the mean volume of contents in the bottles of Honey-Z Assume that the population standard deviation is 20 ml. Calculate the sample size needed if the margin of error is A. 6 ml B. 5 ml C. 4 ml Solution:

Directions: Formulate a null and alternative hypothesis in mathematical notation, and identify if it is one-tailed test or two-tailed test.

1. The average salary of an accountant is P24,620 per month in the Philippines.

Ho: Ha: tailed test: ____

2. A normal smartphone battery manufacturer claims that the mean life of a certain type of battery is more than 650 hours.

Ho: Ha: tailed test: ____

3. According to an international shipping company, a package from US can arrive to Manila in an average of less than 8 business days.

Ho: Ha: tailed test: ____

4. The average price of a certain type of car is greater than P600,000. Ho: Ha: tailed test: ____

5. A research organization reports that the mean of adult grocery shoppers who never buy the store brand in Metro Manila is 300, Ho: Ha: tailed test: ____

6 A study claims that the mean survival period for certain cancer patients treated immediately with chemotherapy and radiation is 24 months). Ho: Ha: tailed test: ____

7. The average pre-school cost for tuition fees last year was P 15,500. The following year, 20 schools had a mean of P 13, 100 and standard deviation of P 2,500. Ho: Ha: tailed test: ____

8. A magazine reports that a typical shopper spends less than 10 minutes in line waiting to check out. A sample of 30 shoppers at the DM Supermarket showed mean of 9.5 minutes with standard deviation of 2.7 minutes. Ho: Ha: tailed test: ____

9. The principal of Mabundok High School claims that the students in his school have above average intelligence. A random sample of 30 students' IQ scores have a mean score of 113. The mean population IQ is 100 with a standard deviation of 15. Is there evidence to support his claim? Ho: Ha: tailed test: ____