Questions: 1-10

Q1.

A random sample of 89 observations produced a mean x = 25.7 and a standard deviation s=2.5.

a.  Find a 95% confidence interval for u.

b.  Find a 90% confidence interval for u.

c.  Find a 99% confidence interval for u.

Q2.

A company wants to test a randomly selected sample of n water specimens and estimate the mean daily rate of pollution produced by a mining operation. If the company wants a 95% confidence interval estimate with a sampling error of 1.1 milligrams per liter (mg/L), how many water specimens are required in the sample? Assume prior knowledge indicates that pollution readings in water samples taken during a day are approximately normally distributed with a standard deviation equal to 7 mg/L.

Q3.

Each child in a sample of 65 low income children was administered a language and communication exam. The sentence complexity scored had a mean of 7.61 and a standard deviation of 8.95. Complete parts a through d.

a.  From the sample, estimate the true mean sentence complexity score of all low-income children.

b.  Form a 90% confidence interval for the estimate, part a

c.  Give a practical explanation of the interval, part b

d.  Suppose the true mean sentence complexity score of middle income children is known to be 15.55 is there evidence that the true mean for low income children differs from 15.55.

Q4.    Q5.     Q6.   Q7.    Q8.     Q9.   Q10. included in the file.