Use the given exponential decay formula to answer the question.
y = ne-kt
Where is the initial quantity, is the time, in hours, k is the decay constant, and y is the final amount.
Potassium-42 is a form of the element Potassium. It is used in medicine and decays over time. A sample of 800 mg is tested. After 30 hours, there is about 140 mg remaining.
Which represents the rate of decay?
A. k = In(0.175) 30
C. k= In(140) 24000
B. k= In(5.714) 30
D. k = In(800) 4200