Given a G.P. with a = 729 and 7^th term 64, determine S₇.

45

How many terms of the G.P. 3, 3², 3³, …… are needed to give the sum 120?

46

The sum of the first three terms of a G.P is 16 and the sum of the next three terms is 128. Determine the first term, common ratio and the sum to n terms of the G.P.

48

Find a G.P. for which sum of first two terms is -4 and the fifth term is 4 times the third term.

49

If the 4^th, 10^th and 16^th terms of a G.P. are x, y and z, respectively. Prove that x, y, z are in G.P.