Question

Following data refers to the jobs (P, Q, R, S) which have arrived at a machine for scheduling. The shortest possible average flow time is ____ days.

Job	Processing Time (days)
P	15
Q	9
R	22
S	12

• A. 31

Answer 1

The correct option is A 31
SPT rule given shortest average

Jobs	Time	Job flow time
Q	9	0 + 9 = 9
S	12	9 + 12 = 21
P	15	21 + 15 = 36
R	22	36 + 22 = 58
		Total = 124

$\text{Job flow time = 124 days}$

$\text{So, applying SPT}$

$\text{Average job flow time}=\frac{124}{4}=31days$