A 1.00-g sample of carbon from a modern

Question

source gave 15.3 disintegrations per minute. A sample of carbon from an “old” source gave 920 disintegrations per hour. What is the age of the “old” sample of carbon? The half-life of carbon-14 is 5.73×103 year.
a. about 34,400 years
b. about 345,000 years
c. about 20 million years
d. less than a few years

Answer 1

Typo: The half-life is 5.7x10^3

Answer 2

Without even doing the math it the change in disintegrations is merely .03333, the sample must have decayed for

d. less than a few years

Answer 3

whoops, i did the math and it came out to about 34,400 years. Sorry for my earlier answer

Answer 4

k = 0.693/t_1/2
k = 0.693/5.7E3 = 1.22E-4

ln(15.3333/15.3) = 1.22E-4(t)
t = about 18 year.

Answer 5

vanden bout

Answer 6

actually drake was right on his first answer i had this question on my homework and it is d. less than a few years :)