Answer:
approximately 313 grams
Step-by-step explanation:
After 1 half-life (14 days), the amount of substance remaining is half of the original amount:
10,000 grams / 2 = 5,000 grams
After 2 half-lives (28 days), the amount remaining is half of the amount remaining after 1 half-life:
5,000 grams / 2 = 2,500 grams
After 3 half-lives (42 days), the amount remaining is half of the amount remaining after 2 half-lives:
2,500 grams / 2 = 1,250 grams
After 4 half-lives (56 days), the amount remaining is half of the amount remaining after 3 half-lives:
1,250 grams / 2 = 625 grams
After 5 half-lives (70 days), the amount remaining is half of the amount remaining after 4 half-lives:
625 grams / 2 = 312.5 grams
Rounding to the nearest whole number, you would have approximately 313 grams remaining after 70 days.