Answer:
36 hours
Explanation:
Notice that you are given the actual table of how the isotope reduces , and it shows that for each period of 6 hours the isotope decays to half of the initial number.
EVery 6 hours, the reduction in number of mg of the isotope goes down in half'
100 mg, then 50 mg, then 25 mg, then 12.5 mg, then 6.25 mg, then 3.125 mg and finally (reaching 1.5625 mg
That was 6 periods of 6 hours each, which totals: 6 time 6 hours = 36 hours
