Exercise: An ethologist is interested in determining the average weight of adult Olympic marmots. It would...
A researcher is interested in determining the average number of years employees of a company stay with the company. If past information shows a standard deviation of 7 months, what size sample should be selected so that at 95% confidence the margin of error will be 2 months or less?
A government agency would like to know the average weight of adult catfish in the wild. The need to know how many fish to sample. The population standard deviation is known to be 16.8 lbs from previous studies. (a) Assuming that they would like to be 90% confident of the results, what is the critical value that corresponds to this given level of confidence? Round to two decimals and remember that critical values are defined to be positive. (b) If...
Question 7 options: A government agency would like to know the average weight of adult catfish in the wild. The need to know how many fish to sample. The population standard deviation is known to be 16.8 lbs from previous studies. (a) Assuming that they would like to be 90% confident of the results, what is the critical value that corresponds to this given level of confidence? Round to two decimals and remember that critical values are defined to be...
A sample of 8 adult elephants had an average weight of 12,300 pounds. The standard deviation for the sample was 22 pounds. Find the 95% confidence interval of the population mean for the weights of adult elephants.
1. How many movies does an adult watch on average each year? A random sample of 29 adults with an average of 128.6 movies and standard deviation of 23.8 movies per year. Construct 95% confidence interval for the average number of movies an adult would watch each year. a. Find the critical value. b. Calculate the margin of error Write the interval. c.
It has been reported that the average adult sends and receives 658 text messages per week. Imagine that we take a random sample of size n = 250 adults from this population and find that the sample standard deviation is 128.5. We know the sampling distribution of the sample mean in this case would have a standard deviation equal to approximately A 15.81. B 128.5. C 1.51. D 8.13. E 658.
A test on a random sample of 50 water balloons yielded a sample average weight of 1.2 pounds. Prior studies have shown that the population standard deviation is 0.2 pounds. Assume that water balloon weight is normally distributed. Construct a 95% confidence interval of the population mean?
In order to determine the average weight of carry-on luggage by passengers on a particular airplane, a sample of 22 pieces of carry-on luggage was weighed. The average weight was 9 kg. It is known that the weight of carry-on luggage is normally distributed and that historical data has shown the standard deviation is 3.45 kg. Determine the critical value for the test statistic (z or t) needed to build an 80% confidence interval for the mean. State the positive...
42. (Problem modified from textbook) A typical adult has an average IQ score of 105 with a standard deviation of 20. If 20 randomly selected adults are given an IQ test, what is the probability that the sample mean scores will be between 95 and 120 points? Round answer to three decimal places (i.e. 0.123) _________Answer
Suppose the coffee industry claimed that the average adult drinks 1.8 cups of coffee per day. To test this claim, a random sample of 40 adults was selected, and their average coffee consumption was found to be 1.95 cups per day. Assume the standard deviation of daily coffee consumption per day is 0.5 cups. Using a = 0.10, complete parts a and b below. a. Is the coffee industry's claim supported by this sample? Determine the null and alternative hypotheses....