If the half-life of k-40 is 1.3 billion years and if a sample rock found on an island is estimated to be 1 billion years old, what percentage of the original parent k-40 would be present in the rock? round your numerical values to the hundredths decimal place.

answer choices

(a) 76.92%
(b) 1.3%
(c) 58.67%
(d) 99.99%

For this case, we must make a rule of three, to find the percentage of the k-40 found in the sample found.

1.3 ----------> 100%

1 -------------> x

Where "x" represents the percentage of k-40 present in the sample found.

Rounding off we have:

76.92%

Option A

add all the numbers and check the ones place.

the answer is 486. as the ones place is more than 4, the estimation will be the next 10 ie, 490

the answer to your question a or b but i am pretty sure it is b. i hope this : )

step-by-step explanation: