The sum of first n terms of two A.P.’s is in the ratio (7n + 2) : (n + 4). Find the ratio of their 5th terms.

Question

Philoid · Accepted Answer

assuming first AP whose first term is a and common difference d

To find: the ratio of 5^th term of a given AP

we know that the sum of AP is given by the formula:

substituting the values in the above equation

Assuming second AP whose first term is A and common difference D

we know that the sum of AP is given by the formula:

substituting the values in the above equation

…. (i)

Given the ratio of the 5^th term is required of both AP’s which is

Substituting n = 9 in (i) we get