Common Ratio

Problem
If 4, 2, 5, and 18 are added respectively to the first four terms of an arithmetic progression, the resulting series is a geometric progression. What is the common difference of the arithmetic progression?
 

Situation
The 4^th term of a geometric progression is 6 and the 10^th term is 384.
 

Part 1: What is the common ratio of the G.P.?
A. 1.5
B. 3
C. 2.5
D. 2
 

Part 2: What is the first term?
A. 0.75
B. 1.5
C. 3
D. 0.5
 

Part 3: What is the seventh term?
A. 24
B. 32
C. 48
D. 96