
2) 5.625 mg will be left
Explanation:
1) Half-life = 17.5 days
initial amount of Arsenic-74 = 90 mg
To get the equation, we will use the equation of half-life:


2) we need to find the remaining amount of Arsenic-74 after 70 days
t = 70

So after 70 days, 5.625 mg will be left
B.
He has used the highest recommended percentages to calculate the amounts for the three categories.
Answer:
So, C, and D.. can easily be marked incorrect. This is because in the question it asks, "Atleast 16" This leaves us with answer choice A and B. Answer choice (A), is a closed circle, while answer choice (B) is an open circle.
Closed circles include the number at the end point (less than/greater than/equal to), and open circles do not (less than greater than).
answer choice A. Closed circle, shifting to the right.
3x = B
(x + 80 = 1/2B) * -3
-3x-240 = -3/2B
-240 = -1/2B
B=480 pennies