Answer:
1) 62.5
2) 50
3) 75
4) 100
Step-by-step explanation:
1)
Because it has a half-life of 25 days, half of it will decay after 25 days.
After [tex]25*4=100[/tex] days, there will be [tex](1/2)^{4}=1/2^{4}=1/16[/tex] of it left.
So, [tex]1000/16=\boxed{62.5}[/tex].
2)
Because it has a half-life of 25 days, half of it will decay after 25 days.
After [tex]25*3=75[/tex] days, there will be [tex](1/2)^{3}=1/2^{3}=1/8[/tex] of it left.
So, [tex]400/8=\boxed{50}[/tex]
3)
Because it has a half-life of 25 days, half of it will decay after 25 days.
After [tex]25*2=50[/tex] days, there will be [tex](1/2)^2=1/2^{2}=1/4[/tex] of it left.
So, [tex]300/4=\boxed{75}[/tex].
4)
The only answer left is [tex]\boxed{100}[/tex] grams. You can solve it the same way you solved the previous steps.