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?
機率兩題求過程解答
2011-05-18 6:19 am
回答 (1)
2011-05-18 8:06 am
✔ 最佳答案
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
收錄日期: 2021-04-23 23:03:51
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110517000051KK01273