MODULE 2 2. A sample of 20 bags of the same brand of candies was selected and found a mean weight of 120 grams. Assume that the population distribution of bag weights is normal. The weight of each bag was then recorded. The population standard deviation is known to be 2.1 grams. Construct a 90% confidence interval for the population mean weight of the candies. 3. A survey of 200 Internet users shows that they spend an average of 2 hours and 22 minutes per day on social networking. If the margin of error is 2.2 hours at 95% confidence, construct the confidence interval. 4. Suppose that a government law office does a study to determine the time needed to complete one personal profile sheet for consultation. It randomly surveys 100 people. The sample mean is 23.6 minutes. There is a known standard deviation of 7.0 minutes. The population distribution is assumed to be normal. Construct a 95% confidence interval for the population mean to complete the form. 5. A camp counselor is interested in the mean number of text messages each child sends during their camp sessions. The population standard deviation is known to be 2.2 text messages. A survey of 20 campers is taken. The mean from the sample is 12.9. Construct a 99% confidence interval for the population mean number of text messages campers send home. 6. A survey of 500 people finds they sleep an average of 7.8 hours per night. If the margin of error at 97% confidence level is 1.3 hours, construct the confidence interval. 7. Suppose you wanted to estimate the mean number of hours that SHS students in certain school spend on their math homework. You don't know the actual mean, but the previous study shows that the standard deviation of all students is 3.2 hours. In a sample of 35 students, the average number of hours spent on homework was 10.4. Create a 90% confidence interval to estimate the average for all SHS students in a school. Assume the underlying population is normally distributed, construct a 95% confidence interval. 8. A quality control specialist for a five-star hotel restaurant takes a random sample of size 12 to check the amount of fruit juice served in the 16-ounce serving size. The sample mean is 15.30 with a population standard deviation of 1.55 ounces. 9. The quantity of hemoglobin in the bloodstream of a man follows a normal distribution with a standard deviation of 2.3 g/dl. Calculate the confidence level for a sample of 15 men, which indicates that the population mean blood hemoglobin is between 14 and 17 g/dl. 10. The weekly sales of an online seller are distributed according to a normal property, with a standard deviation of 900 pesos. A statistical study of sales in the last 10 weeks has found a confidence interval for the mean of weekly sales with extremes of 4,663 and 5,839 pesos. a. What is the average sales over the 10-week period? b. What is the confidence level for this interval