Find the 4th term from the end of the A.P. -11, -8, -5, ..., 49.
Answer: B
To find the nth term from the end, we can use the formula \(l - (n-1)d\), where l is the last term. Here, \(l=49\), \(n=4\), and \(d = -8 - (-11) = 3\). The 4th term from the end is \(49 - (4-1) \times 3 = 49 - 9 = 40\). Alternatively, we can reverse the A.P. to 49, 46, ..., -11. Here \(a=49, d=-3\). The 4th term is \(49 + (4-1)(-3) = 49 - 9 = 40\).