SJF predicts the next CPU burst with an exponential average. If the weight is 0.5, the previous prediction was 10 ms and the actual last burst was 6 ms, what is the next prediction?
Correct answer C. 8 ms
Explanation
The formula is next = a x actual + (1 - a) x previous prediction = 0.5 x 6 + 0.5 x 10 = 8 ms. With a weight of 0.5 recent and past history count equally. A weight of 1 would use only the last burst (6 ms) and a weight of 0 would ignore it (10 ms). SJF needs such an estimate because the true length of the next burst cannot be known in advance.
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