Answer: 48 grams
Step-by-step explanation:
The half-life of an element refers to the amount of time that it takes for half of it to decay.
For instance, if the half life is 2 hours and the element weighs 12 g, the element will only weigh 6g after 2 hours.
The half-life of the above is 6 hours, in 3 hours therefore, it would only have lost of the half that it would have lost in 3 hours which means it would have lost only a quarter.
= 64 * ( 1 - 1/4)
= 48 grams
