Answer:
212 000 yrs
Explanation:
15/16 decay means 1/16 is left
how many halflives is this?
(1/2)^n = 1/16
n = 4 half lives
4 half lives * 53 000 yr/ half life = 212 000 yrs
Explanation: p + ci=pci
h+o=h io
Answer: 3:2