Question

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Answer 1

y = a(1 - r)^t a = initial amount r = decay rate (1 - r) = decay factor t = time, or time since starting time

Answer 2

The general equation for exponential decay is: \[A = A_0(r+1)^t\]
A sub = starting amount @ t = 0
t = time
r = rate of change.

You already have the starting amount, which as I stated previously is A sub-zero. So just plug in the number given.
then plug in for t and solve for r!

This will help you with solving for part b.

Answer 3

For part b, you are just substituting the value you got for r and plug in 9.5 for part b.

Answer 4

Well, im telling you how to solve for r! so you can get how they got 0.75!

Answer 5

Look at the graph and find the coordinates of any point (other than where t = 0) on the graph. (If the axes are not labeled t and A, then the "t" in the equation corresponds to "x" and the "A" corresponds to the "y".)
Replace the t and A in your equation with the coordinates you found previsly and solve this equation for r.

Answer 6

why would u divide? and does dividing 4/7 give you 0.75?!