Given that the half life of 3H is 12.3 years.
The amount of substance left of a radioactive substance with half life of

after t years is given by

Therefore, the number of years it will take for 18% of the original tritinum to remain is given by

Therefore, the number of <span>years that the time could be read at night is 30.4 years.</span>
Answer:
B
Step-by-step explanation:
We can use the law of cosinse:
=
− 2ab cos(C)
Suppose the two sides are a and b, and the angle betweent them is C.
=
− 2*3*4 cos(60)
We can simplify this to get
=25-12=13
c=
Answer choice B
Answer:
-5/4
Step-by-step explanation:
4x=-5
x=-5/4