The operations manager of a body and paint shop has five cars to schedule for repair. He would like to minimize the throughput time to complete all work on these cars. Each car requires body work prior to painting. The estimates of the times required to do the body paint work on each are as follows:

Body work Paint
Car (hrs) (hrs)
A 10 2
B 5 4
C 7 5
D 3 6
E 1 7
a) Where in the optimum sequence should car A be scheduled?
A. first
B. second
C. third
D. fourth
E. fifth
b). What is the optimum sequence (first car to last)?
A. A; B; C; D; E
B. E; D; C; B; A
C. E; B; D; C; A
D. E; D; B; C; A
E. E; B; D; A; C
c) What is the idle time at the paint work center for the optimal schedule?
A. 1 hour
B. 2 hours
C. 4 hours
D. 7 hours
E. 10 hours

Step-1 The smallest time is located in Job E (1 hour). Since the time is in First Work Center (Body), schedule this job first. And eliminate Job E from further consideration.

The sequence is E - ? - ? - ? - ?

Step-2 Then, the smallest time is located in Job A (2 hour). Since the time is in Second Work Center (Paint), schedule this job last. And eliminate Job A from further consideration.

The sequence is E - ? - ? - ? - A

Step -3 Then, the smallest time is located in Job D (3 hour). Since the time is in First Work Center (Body), schedule this job after E. And eliminate Job D from further consideration.

The sequence is E - D - ? - ? - A

Step-4 Then, the smallest time is located in Job B (4 hour). Since the time is in Second Work Center (Paint), schedule this job second last. And eliminate Job B from further consideration.

The sequence is E - D - ? - B - A

Step-5 The only job left to consider is Job C.

The sequence is E - D - C - B - A

a) Where in the optimum sequence will the car A be scheduled?

Answer: Option E – Fifth Position. Refer the sequence for the same based on the Johnson’s rule of sequence.

b). What is the optimum sequence (first car to last)?

Answer : Option B : The sequence is E; D; C; B; A

c) What is the idle time at the paint work center for the optimal schedule?

Answer : C. 4 hours