Question

Which of the following can be insert between $3$ and $19$ as arithmetic means?

• A. $7,11,15$
• B. $6,8,10$
• C. $5,7,9$
• D. $4,8,12$

Answer 1

The correct option is A $7,11,15$

Since, $3$ A.M.'s are inserted between between $3$ and $19$, so
$d=\frac{19-3}{3+1}=4$
Therefore, the A.M.'s are
$3+4,3+2\times 4,3+3\times 4\Rightarrow 7,11,15$