We are given the following equation:
y = y0 e^-0.0001216 t
where y = 1/5 y0, y0 is the original amount
So solving for time t:
1/5 y0= y0 e^-0.0001216 t
t = 13,235.51 years
So the human died about 13235.5 years ago
<span>The molten material then spreads out, pushing the older rock to both sides of the ridge. As the molten material cools, it forms a strip of solid rock in the center of the ridge. Then more molten material flows into the crack. The material splits apart the strip of solid rock that formed before, pushing it aside. Hope this helps! (:</span>