GEOMETRIC PROGRESSION
Posted by
Ravi Kumar at Thursday, May 27, 2010
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Quantities are said to be in geometric progression when they increase or decrease by a constant factor to get the next or previous term respectively.
This can be represented by a, ar , ar^2, ar^3............ where 'a' is the first term and 'r' is the common ratio of the geometric progression. The n th term of the geometric progression is ar^(n1)
Sum of all terms is: a(1r^n)/(1r)
= (r * last term  first term)/(r1)
If three terms are in geometric progression, then the middle term is the geometric mean of the other two terms.
Geometric Mean = (abc)^(1/3)
where a, b, c are in geometric progression
similarly, if n terms a1, a2, a3, …….., an are in G.P then
geometric mean = (a1*a2*a3*a4...an)^(1/n)