A drill manufacturer wants to draw attention to a new design, which, theoretically, allows quicker changes between drill bits. The manufacturer gathers a random sample of 20 amateurs who have some experience using drills around the home. They are asked to complete a pre scribed set of tasks with the new drill and with the old drill (which drill is used first is randomly assigned). The total time to complete the tasks (in minutes) is recorded for each drill. The order of subtraction is (time with the new-style drill - time with the old-style drill).The average difference is -5.2, with a standard deviation of 12.2. Is there sufficient evidence to suggest that the tasks are completed more quickly with the new-style drill? Use α = 0.05.You may assume the differences in completion times are normally distributed.
Answer to relevant QuestionsA company hires a consulting firm to conduct a seminar to improve workers’ sense of self-esteem. Employees are given a test to assess their self-esteem before the seminar, and again afterwards. The test scores are shown ...A random sample of employees is asked to rate the performance of a president. This president is fired, and a new president hired. After six months, the same employees are asked to rate the performance of the new president. A ...A new tool is supposed to reduce the time it takes to assemble a component in a factory. A random sample of workers is selected, and the assembly times are measured with and without the new tool. The average difference in ...A bank with a management training program is considering promotion of one of two trainees in the Metro West division. The bank has asked for feedback for each of the trainees (that is, feedback from managers and peers). The ...A consumer group tested two brands of inkjet printer cartridges for a particular printer to see whether there was a difference in the number of pages produced before the cartridge ran out of ink. The printers were tested in ...
Post your question