When Henry and Anne clean houses together, they can clean a house in 8 hours. When Henry works alone, he can clean a
house in 12 fewer hours than if Anne works alone. How long
will it take Henry to clean a house by himself?

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