$($b$)$ A group of slotted$-$ALOHA stations generate a total of $120$ requests per second including both original and retransmissions. Each request is for a $12\mathrm{.}5$ ms duration slot. Find

$($i$)$ The normalized total traffic on the channel.

$($ii$)$ The Probability of a successful transmission on the first attempt.

$($iii$)$ The Probability of exactly two collisions before a successful transmission.

$(1\mathrm{.}5+1\mathrm{.}5+2)$