16, 11, 8.5, 7.25, ?

Question

16, 11, 8.5, 7.25, ?

Answer 1

16 - 11 = 5

11 - 8.5 = 2.5

8.5 - 7.25 = 1.25

? - 7.25 = 0.625

Answer 2

Every portion is dividing the difference in 1/2.

16-11 = 5

11-8.5 = 2.5. Notice here: 5/2 = 2.5

8.5 - 7.25 = 1.25. Again, here is taking the previous difference and dividing by 2. (2.5 / 2 = 1.25)

Now, take the 1.25 and divide it in half. (1.25/2 = 0.65). You will subtract 7.25 by 0.65 to find the next number.