Radioactive 40k (potassium) decays into 40 ar (argon) with a half-life of 1.25 billion years. when we use this method to estimate the age of a rock, we assume that the rock initially contained no 40 ar, and hence any 40 ar we measure in the rock was produced by the decay of 40k. the oldest rocks on the earth are found in northern canada and have ages of 4.0 billion years, whereas the oldest meteorites have ages of 4.6 billion years. calculate the ratio of 40 ar to 40k that you would expect to find in each of these cases. (hint: assume the initial abundance of 40k is 1, while the initial abundance of 40 ar is 0. what should the relationship be between the abundances of these two isotopes at any given time? )