Answer:

Step-by-step explanation:
The half life is the amount of time it takes a substance to decay to half of its original amount.
Since the radioactive substance has a half life of 1000 years, there will be half of it left after 1000 years.
So, the fraction that will be left after 1000 years is 
Answer:

Step-by-step explanation:
Find the area of the 4 triangles and add them.
Area of triangle = base × height × 0.5
