Question

The 10th common term between the A.P.s 3, 7, 11, 15, .... and 1, 6, 11, 16, ... is

• A. 191
• B. 193
• C. 211
• D. None of these

Answer 1

The correct option is A

191

As, the common difference of the A.P. 3, 7, 11, 15, ... = 7 - 3 = 4 and the common difference of the A.P. 1, 6, 11, 16, ... = 6 - 1 = 5

And, the common terms of both the A.P.s will be in A.P.

So, the common difference of the A.P. of the common terms, d = LCM (4, 5)

$=4\times 5=20$ and its first common term,

a = 11

Now, the tenth common term, $a_{10}=a+(10-1)d$

$=11+9\times 20$

$=11+180=191$

Hence, the correct alternative is option (a).