question_answer

The sum of first eight terms of an A.P. is 66 and the ratio of its \[\mathbf{1}{{\mathbf{3}}^{\mathbf{th}}}\]term to its \[\mathbf{2}{{\mathbf{1}}^{\mathbf{st}}}\]term is 7:11. Find the sum of first 31 terms of this A.P.

A) 885      

B)                                                        765  

C)      668         

D)        826

E) None of these