The given sequence is Geometric Progression. Ratio of any term
to its preceding term is 1:3 so common ratio is 1/3 i.e. r =
1/3.
First term is 729 i.e. a = 729.
Now, we need to find the sixth and seventh terms.
nth term of a G.P. is given by an = arn-1.
So, a6 = 729 x (1/3)6-1 = 729/243 = 3.
a7 = 729 x (1/3)7-1 = 729/729 = 1.