Answer:
4
Step-by-step explanation:
Look at the denominator. It is multiplying by a number each time (because it is geometric and not linear)
Divide any two consecutive denominators to find the common ratio. For example, divide 16 and 4.
16/4 = 4
This works with any two consecutive numbers. Try 256 and 64
256/64 = 4
(Note: Divide with the bigger number on top)
No matter what consecutive denominators you pick you will always get the same number. That's why its called the common ratio. Since you always get 4 with these numbers that means that 4 is the common ratio.