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A counting semaphore is initialized to 8. 3 wait() operations and 4 signal() operations are applied. Find the current value of semaphore variable.

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  1. 9
  2. 5
  3. 1
  4. 4

Answer (Detailed Solution Below)

Option 1 : 9
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Detailed Solution

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Concepts:

V(S): Signal operation will increment the semaphore variable, that is, S++.

P(S): Wait operation will decrement the semaphore variable., that is, S--.

Data:

Initial counting semaphore = I = 8

Wait operation = 3 P

Signal operation = 4 V

Final(current) counting semaphore = F

Formula:

F = I + 4V + 3P

Calculation:

F = 8 + 4(+1) + 3(-1)

∴ F = 9

the resulting value of the semaphore is 9
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