What is the sum of this geometric series? 16+24++81

The formula for a finite geometric series is:



a₁ is the first term of the geometric series. From the given series we can see that the first term of the series is 16.

r is the common ratio of the series. r can be found by dividing a term by its previous term. so r for the given series will be:

r = 24/16 = 3/2

n is the number of terms in the series. We can use the general formula of a Geometric Series to find the number of terms in the given series:



We want to find at which number in the series is 81 located. Using the values, we get:



This means, there are 5 terms in the given series.

Using the values in the formula, we get:



This means, the sum of given geometric series is 211.