Question

The ratio of the 11th term to the 18th term of an arithmetic progression is 2 is to 3 find the ratio of the 5th term to 21st june and also the ratio of the sum of the first five terms to the sum of the first 20 first one terms

Answer 1

Answer:

let a be the 1st term and d be the commom difference of the A.P.

1. Now t11/t18=a+(11-1)d/a+(18-1)d=2:3
2. now solve this equation to get a and d.
3. then find t5/t21.