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1. A new battery supposedly with a charge of 1.5 volts actually has a voltage with a uniform distribution between 1.43 and 1.60 volts. What is (a) the expectation of the voltage? (b) The variance of the voltage? (c) The cumulative distribution function of the voltage? (d) The probability... 顯示更多 1. A new battery supposedly with a charge of 1.5 volts actually has a voltage with a uniform distribution between 1.43 and 1.60 volts. What is (a) the expectation of the voltage? (b) The variance of the voltage? (c) The cumulative distribution function of the voltage? (d) The probability that a battery has a voltage less than 1.48 volts? 2. Jobs arriving at a computer system have been found to require CPU time that can be modeled by an exponential distribution with parameter 1/140 per millisecond. The CPU scheduling discipline is quantum-oriented so that a job not completing within a quantum of 100 milliseconds will be routed back to the tail of the queue of waiting jobs. Find the probability that an arriving job will be forced to wait for a second quantum. Of the 800 jobs coming in during a day, how many are expected to finish within the first quantum?
最佳解答:
1(a) (1.43 + 1.6)/2 = 1.515 (b) (1.6 - 1.43)^2/12 = 0.002408 (c) (x - 1.43)/(1.6 - 1.43) = (x - 1.43)/0.17 (d) (1.48 - 1.43)/0.17 = 0.2941 2 Mean = 140. f(x) = (1/140)exp(-x/140) F(x > 100) = exp(-x/140) = 0.4895 The expected no. to finish within the first quantum = 800(1 - 0.4895) ~ 408
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