For this case we have an equation of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: decrease rate
t: time in years.
Substituting values we have:
7 = A * (0.5) ^ ((1/20) * t)
For t = 45 years we have:
7 = A * (0.5) ^ ((1/20) * 45)
Clearing A:
A = 7 / ((0.5) ^ ((1/20) * 45))
A = 33.3
Answer:
the density of the substance when it was deposited 45 years ago was:
A = 33.3 milligrams per square centimeter
<em>Answer:</em>
<em>D)</em>
<em>Step-by-step explanation:</em>
<em>We know that it cannot be C since z is not involved in this problem.</em>
<em>a) 3/20x</em>
<em>Try with 20 = x</em>
<em>3/440 ≠ 3</em>
<em>A is not the answer.</em>
<em>b) 60x</em>
<em>Try with 20 = x</em>
<em>1800 ≠ 3</em>
<em>B is not the answer.</em>
<em>c) 60/x</em>
<em>Try with 20 = x</em>
<em>3 = 3</em>
<em>Try with 15 = x</em>
<em>4 = 4</em>
<em>D is your answer.</em>
<em>Hope this helps. Have a nice day. Oh, and one more thing. Surprised to see I'm not stealing points?</em>
Answer: Angles a and e
Step-by-step explanation:
Angle a and angle e are also corresponding angles! They both have distinct vertex points and lie on the same side of the transversal.
Answer:
dy/dx = 9x²+2
dy = (9x²+2) dx
dy/dt = (9x²+2) dx/dt
if x = 2 and dx/dt=5 then
dy/dt = (9*2²+2)*5 = 38*5 = 190
B. False questions worth 3 ...
