As a student, you are suspicious that some teachers give easier tests than others. You have heard that Mr. Wilson is one such teacher, and you are thinking of switching to his class. However, you want to be sure that Mr. Wilson's tests are easier. Ms. Hardy has told you that the class average on the first test of the semester was 58.2%. Mr. Wilson did not give out the class average, so you conduct a random sample of 20 students from his class, and get an average mark of 65.4%, with a standard deviation of 18.6. At the 5% level of significance, does this provide evidence that the average mark was higher in Mr. Wilson's class? If so, does this mean that Mr. Wilson's test was easier than Ms. Hardy's? What other explanations should you consider? You may assume the test marks are normally distributed.
Answer to relevant QuestionsThe operations manager at a factory is interested in the lifespan of an electronic component used in one of the factory's machines. The producer of the electronic component claims that it has an average life of 6,200 hours. ...A gasoline refinery has developed a new gasoline that, theoretically, reduces gas consumption per 100 kilometres driven (or, to use a non-metric phrase, provides improved gas mileage).The company wants to gather evidence to ...Suppose you have null and alternative hypotheses as follows: H0: µ = 300 H1: µ < 300 A histogram of the sample data appears normal. The sample mean is 296.5 and the sample size is 40.The sample standard deviation is ...A company wants to estimate the proportion of smokers on staff to within 5%, with 99% confidence. A preliminary estimate of the proportion of smokers is 0.1867. How big a sample size is necessary? A company wants to design a daycare program for its staff. A random sample of 200 employees reveals that 142 have children of daycare age. Construct a 95% confidence interval for the proportion of all employees who have ...
Post your question