Dennis Barry, a hospital administrator, has examined past records from 210 randomly selected 8-hour shifts to determine the frequency with which the hospital treats fractures. The numbers of days in which zero, one, two, three, four, or fi ve or more patients with broken bones were treated were 25, 55, 65, 35, 20, and 10, respectively. At the 0.05 level of signifi cance, can we reasonably believe that the incidence of broken-bone cases follows a Poisson distribution with λ = 2?
A large city fire department calculates that for any given precinct, during any given 8-hour shift, there is a 30 percent chance of receiving at least one fi re alarm. Here is a random sampling of 60 days:
A diligent statistics student wants to see whether it is reasonable to assume that some sales data have been sampled from a normal population before performing a hypothesis test on the mean sales. She collected some sales data, computed x = 78 and s = 9, and tabulated the data as follows:
A supermarket manager is keeping track of the arrival of customers at checkout counters to see how many cashiers are needed to handle the fl ow. In a sample of 500 five-minute time periods, there were 22, 74, 115, 95, 94, 80, and 20 periods in which zero, one, two, three, four, five, or six or more customers, respectively, arrived at a checkout counter. Are these data consistent at the 0.05 level of significance with a Poisson distribution with λ = 3?
A professional baseball player, Lon Dakestraw, was at bat fi ve times in each of 100 games. Lon claims that he has a probability of 0.4 of getting a hit each time he goes to bat. Test his claim at the 0.05 level by seeing whether the following data are distributed binomially (p =0.4). (Note: Combine classes if the expected number of observations is less than 5).
A study compared the number of hours of relief provided by five different brands of antacid administered to 25 different people, each with stomach acid considered strong. The results are given in the following table:
Three training methods were compared to see whether they led to greater productivity after training. The following are productivity measures for individuals trained by each method.
The following data show the number of claims processed per day for a group of four insurance company employees observed for a number of days. Test the hypothesis that the employees’ mean claims per day are all the same. Use the 0.05 level of significance.
Given the measurements in the four samples that follow, can we conclude that they come from populations having the same mean value? Use the 0.01 level of significance.
The manager of an assembly line in a clock manufacturing plant decided to study how different speeds of the conveyor belt affect the rate of defective units produced in an 8-hour shift. To examine this, he ran the belt at four different speeds for fi ve 8-hour shifts each and measured the number of defective units found at the end of each shift. The results of the study follow:.