What is the 27^th term of the A.P 3, 7, 11, ................ ?

This is an arithmetic progression, where first term (a) is 3, an there is a common difference (d) = +4

nth term for an AP generally is

a + (n - 1)d

In this case it is

3 + (n-1).4 = 3 + 4n - 4 = 4n - 1

So, 27th term = 4 x 27 - 1 = 107