As an exercise, we're going to look at data from three zircon samples and try to establish a rock age using those three data points. To start with we need to calculate the ratio of 206Pb to 238U. For the following values in arbitrary concentration units, calculate the ratio of 206Pb to 238U (i. e. 206Pb/238U) to four (4) significant figures. That is, if the value were:. 206Pb = 8,007, 238U = 526,451.238U = 526,451a. 0.9824b. 5123c. 12145