ITPEC IP April 2026 Question 67
ITPEC IP April 2026 — Question 67 of 100
C → A → B — Johnson's rule places the job with the smallest time on X first and the job with the smallest time on Y last.
The overall smallest time is B's 5 minutes on Y, so B goes last. Among A and C, the smallest is C's 6 minutes on X, so C goes first, leaving A in the middle. Schedule: C uses X 0–6, Y 6–14; A uses X 6–14, Y 14–24; B uses X 14–24, Y 24–29. Completion is 29 minutes.
Answer (c)
Why not others: The other sequences create longer idle waits on Y or place B before the end despite its shortest time being on the second machine.
Key rule: For two-machine flow shops, smallest time on the first machine goes early; smallest time on the second goes late.
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