A log contains 60% of the 14C present in a tree how long has log been dead, half life of 14C is 5730 yrs

a) 7560 yrs
b) 4220 yrs
c)3430 yrs
d) 2290 yrs

Hello

exponentiell decline is described by
N = N0*0.5^t/(t/2) with t/2 = half life

60 = 100*0.5^(t/5730) with t = time in years
0.6 = 0.5^(t/5730)
log0.6 = log0.5*(t/5730)
log0.6/log0.5 = t/5730
t = 5730*log0.6/log0.5
t = 4222.8 years old (b)

Regards

so 40% has decaded away - slighlty less than 1 half life so b) most likely c is possible


.6 = .5 ^(4220/5730) = 0.5^.74 YEP

b)