Answers:
- a = 475
- r = -0.5
- f(3) = 59.4
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Explanation:
Any exponential function is of the form y = a*b^x
Comparing that to y = 475*(0.5)^x, we see that a = 475 and b = 0.5
Set b equal to 1+r and solve for r
1+r = 0.5
r = 0.5-1
r = -0.5
The negative r value tells us that the growth rate is -50%, in other words, we have a 50% decay rate. The amount drops by 50% each time x goes up by 1. This is the same as saying the amount cuts in half each time x goes up by 1.
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Lastly, plug in x = 3 to find f(3)
f(x) = 475(0.5)^x
f(3) = 475(0.5)^3
f(3) = 59.375
f(3) = 59.4
