Answer: Hmmmmm that's crazy....
There are a couple of equations one could use for this type of problem, but I find the following to be the easiest to use and to understand.
Fraction remaining (FR) = 0.5n
n = number of half lives that have elapsed
In this problem, we need to find n and are given the FR, which is 1.56% or 0.0156 (as a fraction).
0.0156 = 0.5n
log 0.0156 = n log 0.5
-1.81 = -0.301 n
n = 6.0 half lives have elapsed
Step-by-step explanation:
Just wanted to help. Hopefully it's correct wouldn't want to waster your time ;)