Question

What is the common ratio of this geometric sequence?
1 27
2 18
3 12
4 8
5 16/3
A. -9
B. 2/3
C. 3/2
D. 9

Answer 1

Divide the succeeding term by the previous term,

18 / 27

12 / 18

8 / 12

Answer 2

Test taking strategies--

A. -9: definitely not because it isn't changing that much
B. 2/3: possibly, check it in a second
C. 3/2: If the common ratio is greater than 1, then the terms in the sequence would be getting bigger--but they're getting smaller, so it can't be C
D. 9: no, for the same reason A doesn't work. None of those terms is nine times larger than any other in magnitude.

So B has to be the answer, but just to check:

27*2/3 = 18
18*2/3 = 12
12*2/3 = 8
8*2/3 = 16/3

So B must be the answer