Element X is a radioactive isotope such that every 70 years, its mass decreases by half. Given that the initial mass of a sample of Element X is 610 grams, how much of
the element would remain after 17 years, to the nearest whole number?

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