Answer:
120 grams will be left after 180 years.
Step-by-step explanation:
A radioactive half-life refers to the amount of time it takes for half of the original isotope to decay and its given by

where,
= quantity of the substance remaining
= initial quantity of the substance
= time elapsed
= half life of the substance
From the information given we know that:
- The initial quantity is 480 g,
- The half-life is 90 years,
- 180 years is the time elapsed.
And we want to find how much will be left. For this we use the above formula.

120 grams will be left after 180 years.
Diameter- The line that goes through the circle is the diameter to find the diameter take the radius and multiply it by two
Circumference- Take the radius divide by two and multiply by pi which is 3.14
Answer:
Area of the shaded part is 3.14 square unit.
Step-by-step explanation:
Area of the shaded part = Area of large semicircle - (Area of two small semi circles)
Area of large semicircle with center O = 
= 
= 2π
Area of semicircle with center O' = 
= 
Area of semicircle with center O" = 
Now substitute these values in the formula,
Area of shaded part =
=
= 3.14 square unit
Area of the shaded part is 3.14 square unit.
18 is the answer im pretty sure if its wrong im sorry
Answer:
I think its b
Step-by-step explanation: