$1\mathrm{.}1$ Using the PERT formula, calculate the time $($t$)$ and variance for all activities.T ime in days

Activity Predecessor Optimistic $($a$)$ Most likely

$($m$)$ Pessimistic $($b$)$

A $-6815$

B A $151622$

C A $5812$

D A $101218$

E B $121723$

F C;D $141621$

G E $161819$

H E $51014$

I F;H $369$

J G;H $81317$

K I;J $71115$