Two short bar magnets of length 1 cm each have magnetic moments $1.20\; Am^2$ and $1.00 Am^2$ respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $20.0\; cm$. The value of the resultant horizontal magnetic induction at the mid - point O of the line joining their centre is close to (Horizontal component of earth′s magnetic induction is $3.6 \times 10^{−5} Wb / m^2)$

Question

$\begin{array}{1 1} (1) 3.6 \times 10^{-5} Wb/m^2 \\ (2)2.56 \times 10^{-4} Wb/m^2 \\ (3) 3.50 \times 10^{-4} Wb/m^2 \\ (4) 5.80 \times 10^{-4} Wb/m^2 \end {array}$