Nt is the theoretical minimum number of workstations required and Na is the optimal actual number of workstations that can be achieved with the cycle time in question $(7).$ What is the pair of values of $($Nt$,$ Na$)?$

$($Nt$,$ Na$)=(4,5)$

$($Nt$,$ Na$)=(5,5)$

$($Nt$,$ Na$)=(5,6)$

$($Nt$,$ Na$)=(3,4)$