After 17.1 thousand years, what percentage of the original carbon-14 would be left in an organisms remains?

The 1/2 life of carbon 14 is 5730 years. After 5730 yrs there will be 1/2 of it left. After a second 5730 yrs there will be 1/2 of the 1/2 left or 1/4. Now 5730 + 5730 = 11460yrs. The total yrs considered is 17.1 thousand years or 17,100 years. 17,100-11460 yrs is 5640 yrs. 5640/5730=0.984. For a third 5730 yrs it would be 1/4 x 1/2 of the carbon 14 left, since the amount is diminished by 1/2 each time. So 0.984 x 1/2= 0.492. Since 1/4=0.250 then 0.492 x 0.250=0.123 carbon 14 left at 17,100 yrs. 

The half-life of carbon-14 is 5,730 years, which is a bit short. So, after 17,100 thousand years, there will 12.38% or 12.5% left in an organism’s remains. This is calculated by dividing 17,100 by 5,730 and this gives us a value of 2.98 or 3. So we can expect that after 17.1 years, carbon-14 is reduced thrice. From 100%, it becomes 50%, to 25% and then 12. 38% or 12.5%.

The correct answer is d