Our environment is very sensitive to the amount of ozone in the upper atmosphere. the level of ozone normally found is 6.5 parts/million (ppm). a researcher believes that the current ozone level is not at a normal level. the mean of 27 samples is 6.9 ppm with a variance of 1.21. assume the population is normally distributed. a level of significance of 0.05 will be used. find the value of the test statistic. round your answer to three decimal places.