Question 185684: How do you solve a geomtric mean when the first term is 81, and the fifth term is 16?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! How do you solve a geomtric mean when the first term is 81, and the fifth term is 16?
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Form: a(n) = ar^(n-1)
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a = 81
a(5) = ar^(5-1) = 16
a(5) = 81*r^4 = 16
r^4 = 16/81
r = 2/3
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Geometric sequence:
81, (2/3)81, (2/3)^2*81, (2/3)^3(81) ...
81, 54, 36, 24, 16
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Cheers,
Stan H.
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