The sum of 7 terms of the G.P. 3, 6, 12, ………. is :

1. 181

2. 241

3. 381

4. 421

If 5th, 8th and 11th terms of a G.P. are x, y and z respectively, then which one of the following is correct?

1. y² = x²z²

2. y² = x² + z²

3. y² = xz

4. xyz = 1