Question

A fossilized animal that was killed by a volcano eruption has 12.5 percent of its original amount of carbon-14 remaining; this radioisotope has a half-life of 5730 years. How long ago did the volcano erupt?


34,380 years ago

22,920 years ago

17,190 years ago

9,168 years agoA fossilized animal that was killed by a volcano eruption has 12.5 percent of its original amount of carbon-14 remaining; this radioisotope has a half-life of 5730 years. How long ago did the volcano erupt?


34,380 years ago

22,920 years ago

17,190 years ago

9,168 years ago

Answer 1

is this the same question? just posted twice?

Answer 2

Yes sorry! I posted it in the wrong category at first

Answer 3

that's fine, just curious

Answer 4

use the formula

F = P(1/2)^(t/H)

where

F = final amount in t years
P = initial amount
t = time in years
H = halflife

Answer 5

in this case

F = 0.125
P = 1
t = unknown (this is what we want to solve for)
H = 5370

Answer 6

Im so confused! I just dont understand this lesson at all and I was sick so missed the lesson in class.

Answer 7

this looks completely foreign?

Answer 8

Ok i got 16110? am i close?

Answer 9

let me check

Answer 10

oh sry meant to say H = 5730

Answer 11

ok so 17190 would be correct? what about the other 2 questions>

Answer 12

F = P(1/2)^(t/H)


0.125 = 1*(1/2)^(t/5730)


0.125 = (1/2)^(t/5730)


ln(0.125) = ln((1/2)^(t/5730))


ln(0.125) = (t/5730)*ln(1/2)


5730*ln(0.125)/ln(1/2) = t


t = 5730*ln(0.125)/ln(1/2)


t = 17,190

Answer 13

yep it's 17190

Answer 14

thank you so much I figured them out!

Answer 15

you're welcome