Exam 14: Exercises

The time (in number of days) until maturity of a certain variety of tomato plant is Normally distributed, with mean and standard deviation ?= 2.4. You select a simple random sample of four plants of this variety and measure the time until maturity. The four times, in days, are as follows: 63 $\quad$ 69 $\quad$ 62 $\quad$ 66 Based on these data, what is the 99% confidence interval for ?, in days?

The pH measurements of water specimens from various locations along a given river basin are Normally distributed, with standard deviation σ= 0.3. The average pH of water specimens from 4 randomly selected locations on this river basin is x̄= 7.8. Based on these data, what is the value for the margin of error for a 95% confidence interval for μ?

You carry out a study to investigate the decline in cod populations off the coast of Canada. To carry out a hypothesis test, you must decide which sample size should be used. Which factors affect your decision?

The distribution of total body protein in adult men with liver cirrhosis is approximately Normal, with standard deviation σ= 0.1 kg. A 95% confidence interval for the true mean total body protein of adult men with liver cirrhosis, based on 67 randomly selected adult males with liver cirrhosis, has a margin of error of 0.024 kg. How would a 99% confidence interval based on the same study compare to the 95% confidence interval?