After the first term, each term in a sequence is k times the preceding term and p is the first term of the sequence. If the ratio of the seventh term to the third term is 16, what is a possible value of k?

Say the 3rd term is a. Then the 4th term is ka, the 5th term is (k^2)a, the 6th term is (k^3)a, and the 7th term is (k^4)a.

The question says that the ratio of the 7th term to the 3rd term, (k^4)a to a, is 16.

k = 2 or k = –2