The first three terms of a geometric series are p(3q + 1), p(2q + 2) and p(2q − 1), where p and q are non-zero constants.

a. Show that one possible value of q is 5 and find the other possible value.

b. Given that q = 5, and the sum to infinity of the series is 896, find the sum of the first 12 terms of the series. Give your answer to 2 decimal places.