The
half-life of this radioactive isotope is 9 months for it decreases to
one-fourth its original amount in 18 months. Half-life means a certain length
of time after which half of the amount of radioactive element has decayed. 
Therefore,
the half-life of this particular isotope is 18 months. After 18 months the
isotope was at one-half, then another 18 months, the isotope was at one-fourth,
which is 9 months where one-fourth is one-half of one half.
 
        
             
        
        
        
Well, according to what I see on the news usually I'd say...
Answers ~ A, B, C, E, D
I hope this helps! ^w^ Brainliest if can? :o
 
        
             
        
        
        
Answer:
D is the correct answer
Explanation:
A) shows low accuracy and high precision since they missed the bull's-eye but are all grouped together.      
B) Shows high accuracy and high precision
C) Shows high precision
D  is the only one that shows both low accuracy and low precision
 
        
             
        
        
        
A.	The object is made of stone or metal, which always sink.
B.	The force of gravity is stronger than the buoyant force.
C.	The buoyant force is stronger than the force of gravity.
D.	The mass of the item is greater than its gravity
The answer is C
 
        
             
        
        
        
If speed = distance/time , then time = speed/distance. 
So...
Speed of light = 3*10^8(m/s)
Average distance from Earth to Sun = 149.6*10^9(m)
Therefore, t=(3*10^8(m/s))/(149.6*10^9(m))
I hope this was a helpful explanation, please reply if you have further questions about the problem. 
Good luck!