Assume the distribution of measurements to be approximately normal.
a) Construct a
b) What can we assert with
The value of mean is 23,500 kilometres, population standard deviation is 3,900 and sample size
From the standard normal distribution table, for the
The confidence interval formula for the population mean is,
b) The required formula is obtained below:
Substitute 3,900 for
A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 13 subjects had a mean wake time of 101.0 min. After treatment, the 13 subjects had a mean wake time of 94.6 min and a standard deviation of 24.9 min. Assume that the 13 sample values appear to be from a normally distributed population and construct a
What does the result suggest about the mean wake time of 101.0 min before the treatment? Does the drug appear to be effective?
The confidence interval ▼ does not include| includes the mean wake time of 101.0 min before the treatment, so the means before and after the treatment ▼ could be the same |are different. This result suggests that the drug treatment ▼ does not have | has a significant effect.
The average zinc concentration recovered from a sample of measurements taken in 36 different locations in a river is found to be 2.6 grams per liter. Find the 95% confidence intervals for the mean zinc concentration in the river. Assume that the population standard deviation is 0.3 gram per liter.
In a science fair project, Emily conducted an experiment in which she tested professional touch therapists to see if they could sense her energy field. She flipped a coin to select either her right hand or her left hand, and then she asked the therapists to identify the selected hand by placing their hand just under Emily's hand without seeing it and without touching it. Among 358 trials, the touch therapists were correct 172 times. Complete parts (a) through (d).
a) Given that Emily used a coin toss to select either her right hand or her left hand, what proportion of correct responses would be expected if the touch therapists made random guesses? (Type an integer or a decimal. Do not round.)
b) Using Emily's sample results, what is the best point estimate of the therapists' success rate? (Round to three decimal places as needed.)
c) Using Emily's sample results, construct a
Round to three decimal places as needed - ?
People with high blood pressure suffer from hypertension. A study of the lipid profiles of hypertensive patients was carried out and the results published in Biology and Medicine (Vol. 2, 2010). Data on fasting blood sugar (milligrams/deciliter) and magnesium (milligrams/deciliter) in blood specimens collected from 50 patients diagnosed with hypertension were collected. The accompanying MlNlTAB printout gives 90% confidence intervals for the mean fasting blood sugar (FBS) and mean magnesium level (MAG). a. Locate and interpret the 90% confidence interval for mean fasting blood sugar on the printout. b. Locate and interpret the 90% confidence interval for mean magnesium level on the printout. c. If the confidence level is increased to 95%, what will happen to the width of the intervals? d. If the sample of hypertensive patients is increased from 50 to 100, what will likely happen to the width of the intervals?