octor wants to estimate the mean trigliceride level of all 20- to 29-year-old females (in milligram per deciliter, mg/dL). How many subjects are needed to estimate the mean trigliceride level within 4 mg/dL with 95% confidence assuming s=16.2 mg/dL from an earlier study? The doctor needs to sample at least ??  20- to 29-year-old females.

A marketing specialist wants to estimate the average amount spent by visitors to an online retailer's newly-designed website. From the data in a preliminary study she guesses that the standard deviation of the amount spent is about 14 dollars. Question 1. How large a sample should she take to estimate the mean amount spent to within 5 dollars with 95% confidence? (Round your answer up to the next largest integer).

Glaucoma is a leading cause of blindness in the United States, N. Ehlers measured the difference in corneal thickness (in microns) between the two eyes of eight patients. Each patient had one eye that had glaucoma and one eye that was normal. The difference was measured as the corneal thickness of normal eye – corneal thickness of eye with Glaucoma. Corneal thickness is important because it can mask an accurate reading of eye pressure. Question:If the t statistic falls below the effect size in which we reject the null, but the p value is greater than 0.05. Do i reject the null? As my scenario had no population mean because the differences were recorded, do i set a test value of 10 or keep it at 0?

The mean score for first exam in your first organic chemistry class (section A) was 60, with a standard deviation of 5. Your score on the exam was 70. A. How many standard deviations above the mean is your score?

Standardized measures seem to indicate that the average level of anxiety has increased gradually over the past 50 years. (Twenge, 2000). In the 1950s , the average score on the Child Manifest Anxiety Scale was ?= 15.1. A sample of n = 16 of today's children produces a mean score of M = 23.3 with SS = 240.  Based on the sample, has there been a significant increase in the average level of anxiety since the 1950s?  Use a one-tail test with α= .05. ****Is the critical region 1.753? Positive or Negative?**

Glaucoma is a leading cause of blindness in the United States, N. Ehlers measured the difference in corneal thickness (in microns) between the two eyes of eight patients. Each patient had one eye that had glaucoma and one eye that was normal. The difference was measured as the corneal thickness of normal eye – corneal thickness of eye with Glaucoma. Corneal thickness is important because it can mask an accurate reading of eye pressure. Question: Write a report summarizing your findings When writing the report consider that medical staff estimate that a difference of 4.5 microns or more could impact on their ability to interpret eye pressure correctly.

You are conducting a study to see if the average female life expectancy is significantly more than 93. Your sample data (n=15) produce the test statistic t=2.33. Find the p-value accurate to 4 decimal places.

We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately �=76.4. We would like to be 95% confident that the estimate is within 0.5 of the true population mean. How large of a sample size is required?�=

A water hose manufacturer has developed a light-weight hose for home owners. Besides being constructed of a lightweight material. one of the characteristics of the hose is that it shrinks when it is not in use. When in use, the length of hose extends to its advertised length of 50 feet. Twenty hoses are tested to see if the hoses extend to the length of 50 feet. The sample mean of the length of the hoses is 49 1/2 feet with a s of 15 inches. Test the hypothesis at alpha = .01 that the hoses are not equal to 50 feet.

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately 79.8. You would like to be 95% confident that your estimate is within 5 of the true population mean. How large of a sample size is required?