Achemical company makes two brands of antifreeze. the first brand is 70% pure antifreeze, and the second brand is 95% pure antifreeze. in order to obtain 180 gallons of a mixture that contains 90% pure antifreeze, how many gallons of each brand of antifreeze must be used?

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