the basic block company needs to produce

$4$

$0$

$0$

$0$

$$boxes of blocks in a

$4$

$0$

$$hour work week. the process of making blocks can be broken down into

$6$

$$elements$.$ the presedence and time requirements for each element can be found in the table below:

A

$($

performance time

$=$

$0$

$.$

$1$

$0$

$$min

$)$

B

$($

precedence

$=$

$$A

$)$

$($

performance time

$=$

$0$

$.$

$4$

$0$

$$min

$)$

C

$($

precedence

$=$

$$A

$)$

$($

performance time

$=$

$0$

$.$

$5$

$0$

$$min

$)$

D

$($

performance time

$=$

$0$

$.$

$2$

$0$

$$min

$)$

E

$($

precedence

$=$

$$C

$,$

D

$)$

$($

performance time

$=$

$0$

$.$

$6$

$0$

$$min

$)$

F

$($

precedence

$=$

$$B

$,$

E

$)$

$($

performance time

$=$

$0$

$.$

$4$

$0$

$$min

$)$

what is the efficiency of a balanced assembly line?

a

$.$

$9$

$1$

$.$

$7$

$\%$

b

$.$

$1$

$0$

$9$

$.$

$1$

$\%$

c

$.$

$7$

$3$

$.$

$3$

$\%$

d

$.$

$6$

$1$

$.$

$1$

$\%$

the good answer is A: $91\mathrm{.}7\%$