Question

a radiotactive isotope lose 1/5 of its atoms in a sample decay after 14 years. find the half life.

Answer 1

if k is the half-life time, then

.8 = 1 (1/2)^(14/k)
log .8 = (14/k)(log .5)
14/k = log.8/log.5
k/14 = log.5/log.8
k = 14(log.5)/log.8 = 43.48

Answer 2

thanks :D