Estimating Population Mean Sigma Known

Overproduction of uric acid in the body can be an indication of cell breakdown. This may be an advance indication of illness such as gout, leukemia, or lymphoma. Over a period of months, an adult male patient has taken eight blood tests for uric acid, which had the mean concentration of 5.3 mg/dl. The distribution of uric acid in healthy adult males can be assumed to be normal with a standard deviation of 1.85 mg/dl. The level of confidence sis 95%. What is the margin of error E?

• 4.07 mg/dl

• 1.82 mg/dl

• 1.48 mg/dl

• 1.28 mg/dl

Suppose an archaeologist discovers seven fossil skeletons from a previously unknown species of miniature horse. Reconstructions of the skeletons of these seven miniature horses show the shoulder heights (in centimeters) to be 45.3, 47.1, 44.2, 46.8, 46.5, 45.5, 47.6 Assume that the population of shoulder heights is approximately normal. Find the 99% confidence interval for the mean of the shoulder heights of the entire population of such horses.

• (45.4 cm, 48.7 cm)

• (46 cm, 48 cm)

• (45 cm, 48 cm)

• (44.5 cm, 47.8 cm)

When all other quantities remain the same, how does increasing the sample size affect the width of a confidence interval?

• nothing changes

• CI width increases

• CI width decreases

When all other quantities remain the same, how does increasing the population standard deviation affect the width of a confidence interval?

• nothing changes

• CI width increases

• CI width decreases

Select the formula to calculate the minimum sample size n, to obtain some maximal margin of error.

• a

• b

• c

• d

• e

• 0.9130

• 0.1788

• 0.1814

• 0.5596

A certain variety of table grapes has fruit diameters that are distributed normally with mean 13 mm and standard deviation 2 mm. If you take a sample of 16 grapes, approximately what value represents the 80th percentile for the sample mean?

• 12.60

• 12.58

• 13.42

• 13.40

The mean July daily rainfall in Hulu Kinta is 10 mm and the standard deviation is 1.5 mm. What is the probability that the average rainfall for the month of July will be less than 9.5 mm? (31 days in July)

• 0.0918

• 0.3707

• 0.9686

• 0.0314

The ages of the population of people living in Meru, Malaysia are normally distributed with a mean of 43 and standard deviation of 14. If you take a sample of 49 people, what it the probability the sample mean will be greater than 46?

• 0.9332

• 0.0668

• 0.5832

• 0.0013

An article investigated whether education programs for nurses improve the outcomes for their older patients. The standard deviation of the lengths of hospital stay on the intervention ward is 8.3 days. What is the probability that the sampling error made in estimating the mean length of stay of a sample of 80 patients will be at most 2 days?

• 0.9692

• 0.9846

• 0.9544

• 0.9772