A certain element has a half life of 4.5 billion years. a. You find a rock containing a mixture of the element and lead. You determine that ​30% of the original element​ remains; the other ​70% decayed into lead. How old is the​ rock?Analysis of another rock shows that it contains ​5% of its original​ element; the other ​95% decayed into lead. How old is the​ rock?

Acd that is originally priced at $15.85 red-tagged for the sale. what is the sale price of the cd

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2) a. -5x^2 + 4xy + 9y^2 b. -5x^2 - 4xy + 9y^2 c. -5x^2 + 12xy + 4y^2 d. -5x^2 - 4xy - 5y^2

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