Q$4.$ In a computer lab there is a $75\%$ chance that a student ends up using a computer with

a small monitor $($call this event $M).$ In this case, the length of time that the student works

is $x|MN(=40,=3).$ However, if the monitor is large $($call this $\{$:$M^c),$ the length of

time that the student works is increased by $N(=5,=1).$

$($i$)$ What is the distribution of $x|M^c?$

$($ii$)$ Calculate $Pr(x43|M)$ and $Pr(x43|M^c).$