physics :

Question 7 10 pts A 5000-Ci 60Co source is used for cancer therapy. After how many years does its activity fall below 3.59x 103 Ci? The half-life for 60Co is 5.2714 years. Your answer should be a number with two decimal points. Question 8 10 pts An archeologist nds an ancient re pit containing partially consumed rewood, and the carbon-14 content of the wood is only 12.5 % that of an equal carbon sample from a present-day tree. What is the age in years of the ancient site? Your answer should be in the form of N x 104 years. Enter only the number N with two decimal places, do not enter unit. Carbon-14 has a half-life of 5 730 years