In 2004 the company reported that the national college freshman-to-sophomore retention rate held steady at 7496 over the previous four years. consider random samples of 400 freshmen who took the act. use the 68—95—99.7 rule to describe the sampling distribution model for the percentage of those students we expect to return to that school for their sophomore years. do you think the appropriate conditions are met?

Ur environment is very sensitive to the amount of ozone in the upper atmosphere. the level of ozone normally found is 4.04.0 parts/million (ppm). a researcher believes that the current ozone level is not at a normal level. the mean of 2525 samples is 4.44.4 ppm with a standard deviation of 0.80.8. assume the population is normally distributed. a level of significance of 0.020.02 will be used. make the decision to reject or fail to reject the null hypothesis. answer tables