Find the common ratio between each number given:
8/4 = 2
16/8 = 2
32/16 = 2
The common ratio is constant at 2, which means the next number would be 32 x 2.
A geometric series equation is written as an = a1r^n-1
Where a1 is the first term, r is the ratio and n is the term you want to find.
r was determined to be 2. The first term is given as 4 ( the first number in the series).
This means the equation becomes an = 4(2)^n-1
The answer would be B.
