1. The problem statement, all variables and given/known data The total mass of carbon in living systems is estimated to be 7.7x10^17 g. Given that the total mass of carbon on Earth is estimated to be 7.7x10^22 g, what is the ratio of carbon atoms in living systems to the total carbon atoms on Earth? Report your answer in percent and in ppm. Do not forget to show your calculation work. 2. Relevant equations 3. The attempt at a solution 1 * (e^(-5)) = 0.006737947 or 22/17 would give me the percent of 77. I have been going round and round with this question for the last few weeks and now it is due in a couple of days!! Also, I want to double check - is total mass of carbon the same as carbon atoms?