A mobile computer network consists of a number of computers (called nodes) that communicate with each other while moving throughout a region. A node that is out of transmission range of the other nodes, so that it is unable to communicate, is said to be partitioned. In studies carried out at the Colorado School of Mines, S. Kurkowski found that in a network containing 187 nodes in which destinations were chosen at random from a uniform distribution, 19 nodes were partitioned. J. Norman found that in a network containing 170 nodes whose movements mimicked those on a college campus, 30 nodes were partitioned. Let px represent the population proportion of partitioned nodes in the network that mimicked those on a college campus and let py represent the population proportion of partitioned nodes in the network whose destinations were chosen at random. Find a 99% confidence interval for the difference px-py. Round the answers to four decimal places. The 99% confidence interval is ( ' ).

A market with 168 operating firms has the following distribution of average number of workers in various income groups: Income groups : 150-300 300-500 500-800 800-1200 1200-1800 No. of firms : 40 32 26 28 42 Average No. of workers : 8 12 7.5 8.5 4 Find the average salary paid in the whole market.

3) The following two sets of Excel output use are from the same data set as described above, but the first set of output is for the set of 35 CEO’s that earn the lowest total compensation and the second set of output is for a set of 40 CEO’s that earn the highest total compensation. a) What is heteroscedasticity? b) Why is heteroscedasticity a problem? c) Based on a comparison of the two sets of output, does it appear that there is heteroscedasticity in the data set? Explain.

A group of veterinarians at a major veterinary hospital was interested in investigating a possible link between enteroliths, stones that form in the colon of horses, and diet. They decided to conduct a survey of feeding practices of horses in the hospital's state. They created a survey questionnaire and decided to administer it to the owners of every fifth horse being treated at the hospital. The population of interest is:       A)all horses in the state.     b) all horses that are diagnosed with enteroliths.   C) None of the answer choices is correct.   D)all horses brought to the clinic.

1. A realtor sells houses in three different neighborhoods in the city—A, B and C. He sells ranch style homes and two-story homes. Last year, 60% of his sales were in neighborhood A, while neighborhood B made up 25% and neighborhood C was 15% of the sales. Only 10% of the houses in neighborhood A were ranches, compared with 40% for neighborhood B and 50% for neighborhood C. Suppose we randomly select one of the homes he sold in one of these three neighborhoods. (1) What’s the probability that the home is a ranch? (Enter a decimal as your answer, round to the nearest thousandth when necessary) (2) If the home is a ranch, what’s the probability that it is in neighborhood C? (Enter a decimal as your answer, round to the nearest thousandth when necessary)