Find Each Sum Or Difference. 1) 12 + (- 3)
2) -7 + 4
3) -8 + (- 6)
4) -42 + 15
5) 32 - ( - 8)
6) -18 - 12
7) -15 - (-14)
8) -76 - 5

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