Answer:
![\Sigma_{k=1}^{n}[3(\frac{10}{9} )^{k-1}]](https://tex.z-dn.net/?f=%5CSigma_%7Bk%3D1%7D%5E%7Bn%7D%5B3%28%5Cfrac%7B10%7D%7B9%7D%20%29%5E%7Bk-1%7D%5D)
Step-by-step explanation:
A geometric sequence is a list of numbers having a common ratio. Each term after the first is gotten by multiplying the previous one by the common ratio.
The first term is denoted by a and the common ratio is denoted by r.
A geometric sequence has the form:
a, ar, ar², ar³, . . .
The nth term of a geometric sequence is 
Therefore the sum of the first n terms is:

Given a geometric series with a first term of 3 and a common ratio of 10/9, the sum of the first n terms is:
Answer:
The savings of Sid and Tim will be in 17:9 in 6 weeks.
Step-by-step explanation:
Initial savings of Sid = £ 13
Initial savings of Tim = £ 0
For each successive week Sid saved = £ 3.5
For each successive week Tim saved = £ 3
Let us assume that after "x weeks" the amounts of Sid and Tim are in ratio 17:9.
If Sid saves £ 3.5 in one week, in x weeks he will £ 3.5x. Since he had £ 13 initially, total amount he would have in x weeks will be £ (13 + 3.5x)
If Time saves £ 3 one week, in x weeks he will save £ 3x. Since, he didn't have any money initially, in x weeks he would have saved £ 3x
The ratio of their savings in x weeks would be 17:9
So,
Sid's saving : Tim's saving = 17 : 9
Using the values of expressions, we get:

This means, the savings of Sid and Tim will be in 17:9 in 6 weeks.
Answer:
92/69 cannot be simplified
Step-by-step explanation:
9n + 6 = 456
9n = 456 - 6
9n = 450
n = 450/9
n = 50
I believe this is the answer, though i'm not sure.