When platinum-197 undergoes a nuclear decay it becomes gold-197. The half life of platinum-197 is 20 h
a) how long would it take to turn 90% of a 1kg of platinum-197 into gold.
0.90/1=0.5^(t/20) log of both sides
log 0.90=t/20 log0.5
answer in my book is 66.4 hours! what am i doing wrong! Thanks in advance!