The radioactive substance Iridium-192 has a half-life of 73.83 days. How many days would it take for a sample of Iridium-192 to decay to 1% of its original amount? Round your answer to the nearest integer.
1% ==100% x 1/2^(d/73.83)
0.01 ==1 x 1/2^(d / 73.83)
d / 73.83 ==log(0.01) / log(1/2)
d / 73.83 == 6.6438561898
d ==73.83 x 6.6438561898 ==490.5159==~491 days
already posted here: https://web2.0calc.com/questions/help_85497
-nerdiest.
