The 10th common term between the series 3 + 7 + 11 + ... and 1 + 6 + 1

1.	The 10th common term between the series 3 + 7 + 11 + ... and 1 + 6 + 11 + ... is(A) 191 (B) 193(C) 211(D) None of these
Answer» (A) is the correct answer. The first common term is 11. Now the next common term is obtained by adding L.C.M. of the common difference 4 and 5, i.e., 20. Therefore, 10^th common term = T₁₀ of the AP whose a = 11 and d = 20 T₁₀ = a + 9 d = 11 + 9 (20) = 191

The 10th common term between the series 3 + 7 + 11 + ... and 1 + 6 + 11 + ... is(A) 191 (B) 193(C) 211(D) None of these

Answer»

(A) is the correct answer.

The first common term is 11.

Now the next common term is obtained by adding L.C.M. of the common difference 4 and 5, i.e., 20.

Therefore, 10^th common term = T₁₀ of the AP whose a = 11 and d = 20

T₁₀ = a + 9 d = 11 + 9 (20) = 191