A geometric progression has common ratio = 3 and last term = 486. If the sum of its terms is 728; find its first term.

Find the sum of G.P. : 3, 6, 12, ……., 1536.

In a G.P., the ratio between the sum of first three terms and that of the first six terms is 125 : 152. Find its common ratio.

If the sum of 1 + 2 + 2² + …….. + 2^{n - 1} is 255, find the value of n.