A certain element has a half-life of 2.5 billion years.
a. You find a rock containing a mixture
of the element and lead. You determine that 35 % of the original element remains; the other 65 % decayed into lead. How old is the rock?
a. The rock is approximately billion years old.
b. Analysis of another rock shows that it contains 5% of its original element; the other 95% decayed into lead. How old is the rock? (Round to one decimal place as needed.)
b. The rock is approximately billion years old.
Please show work or how you got the answers .... I am totally lost !!!! Also need answer by tomorrow Sunday 8-25-2019.