Suggestion

An arithmetic progression is such that the sum of the first \(10\) terms is \(3\) times the sum of the first \(5\) terms. Find the ratio of the \(10\)th term to the \(5\)th term.

If \(S_n\) is the sum of the first n terms, do we have a formula for \(S_n\)?

If \(u_n\) is the nth term, do we have a formula for \(u_n\)?

Given further that the 5th term is \(0.14\), calculate the sum of the first 200 terms.

Can we find the common difference with this added information?