Answer:
6.25% of the original amount
Explanation:
half-life means that half is gone for every certain period of time. Because the half life is 1 month, only half of the 'radionulide' is left every month.
after 1 month= 50%
after 2 months= 25%
after 3 months= 12.5%
after 4 months= 6.25%
