Which answer describes this type of series - 20-18-15-11 - ...

A). Arithmetic

B). Geometric

C). Neither

D). Both

The answer is C) Neither because their is no consistency in adding, subtracting, multiplying, or dividing

Arithmetic sequences have a common difference, while Geometric sequences have a common ratio.

In the sequence - 20, - 18, - 15, - 11 ..., there is not a common difference. This is because there is a + 2 increase between - 20 and - 18 but a + 3 difference between - 18 and - 15, then + 4 increase between - 15 and - 11.

This means it is not Arithmetic, which means it can't be both either.

This leaves us with B and C, so we have to see if there is a common ratio.

To find common ratio, divide any 2 terms in the sequence.

Let's choose - 18 and - 15.

-18 / - 15 = 1.2

Now let's see if this works for each term.

To do this, multiply each term by 1.2 to see if it results in the next term.

-20 • 1.2 = - 24 This doesn't work, so there is no common ratio.

This means the sequence is neither Arithmetic nor Geometric.

So the answer is C. Neither.