How many terms of the geometric series 6+3+3/2+... must be taken to give a sum of 11+13/16? What is the sum of an infinite amount of terms?

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r is 1/2 The equation for the infinite sum is a/(1-r) where a is the first term. so 6/(1-1/2) = 12. The formula for a finite sum is a(1-r^n)/(1-r) 6(1-.5^n)/(1-.5) = 11 + 13/16 and solve for n using logs.