$$

$1.$ Given: PERT Project Data

Activity

Immediate Predecessor$($s$)$

Optimistic time

Most Likely time

Pessimistic time

A

$-$

$1$

$2$

$4$

B

$-$

$5$

$6$

$7$

C

$-$

$2$

$4$

$5$

D

A

$1$

$3$

$4$

E

C

$4$

$5$

$7$

F

A

$3$

$4$

$5$

G

B$,$D$,$E

$1$

$2$

$3$

Find the probability of completing the project in $12$ weeks. In $10-13$weeks. Use upper and lower limits$.$