Metahe Action Toy Company has decided to manufacture a new train $?$ ?set, the production of which is broken into six steps. The demand for the train is units per $?40-$ hour workweek:

$$ ?

Task

Performance Time

$?($ seconds $)$

Predecessors

A

$20$

$-$

B

$30$

A

C

$14$

A

D

$15$

A

E

$12$

$?$ B $,$ ?C

F

$27$

$?$ D $,$ ?E

?

This exercise only contains parts $?$ ?b $,$ ?c $,?$ ?d $,$ ?e $,$ ?and f $.$

Part $2$

$?$ b $)$ ?Given the $?$ ?demand, the cycle time for the production of the new train set $?=$