The ratio of sums of n-terms of two arithematic progressions is (3n-13):(5n+21). The ratio of 24th term of the two series is?

let first term and common difference of first AP be A & D and for the second AP be "a" & "d"

 

therefor (3n-13)/(5n+21)=(n/2(2A+(n-1)D))/(n/2(2a+(n-1)d))

 

therefor (3n-13):(5n+21)=(2A+(n-1)D))/(2a+(n-1)d)

 

now putting n=47 on both sides

 

(3*47-13)/(5*47+21)=(A+23D)/(a+23d)

 

therfor ratio of there 24 th term=1/2