math
posted by Bob on .
sorry for before it is my first time using this website and this is the real question
in a geometric series t1=23,t3=92 and the sum of all of the terms of the series is 62813. How many terms are in the series?

t1 = 23 > a = 23
t3 = 92 >ar^2 = 92
divide them
r^2 = 4
r = ± 2
sum(n) = a(r^n  1)/(r1) = 62813
If r = 2
23( 2^n  1)/(21) = 62813
2^n  1 = 2731
2^n = 2732
but ....
n has to be a whole number, since it stands for the number of terms
2732 is NOT a power of 2,
so even though you typed it again with a correction , the question is still flawed. 
Answer is 13 terms