#23. A health care professional wishes to estimate the birth weights of infants. How large a sample must be obtained if she desires to be 90% confident that the true mean is within 2 ounces of the sample mean? Assume standard deviation = 8 ounces

#16. For a sample of 24 operating rooms... the mean noise level was 41.6 decibels and the standard deviation was 7.5. Find the 95% confidence interval of the true mean of the noise levels in the operating room.

#8. A CBS News/ New York Times poll found that 329 out of 763 adults said they would travel to outer space in their lifetime, given the chance. Estimate the true proportion of adults who would like to travel to outer space with 92% confidence.

#18. Obesity is defined as a body mass index (BMI) of 30 kg/m² or more. A 95% confidence interval for the percentage of US adults aged 20 years and over who were obese was found to be 22.4 to 23.5%. What was the sample size?

#19. Nearly one half of Americans aged 25-29 are unmarried. How large a sample is necessary to estimate the true proportion of unmarried Americans in this age group within 2(1/2) [two and a half] percentage points with 90% confidence?