The demand for a certain item is random. It has been

estimated that monthly demand of the item has a normal

distribution with a mean of $780$ units. The unit price of the

item is Rs$\mathrm{.}25.$ ordering cost is Rs$\mathrm{.}28$ and the inventory

carrying cost is estimated to be $35$ per cent year. Determine

$($a$)$ EOQ, $($b$)$ Total inventory cost with EOQ