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Fundamentals of Probability and Statistics for Engineers

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68 <strong>Fundamentals</strong> <strong>of</strong> <strong>Probability</strong> <strong>and</strong> <strong>Statistics</strong> <strong>for</strong> <strong>Engineers</strong>p X(x)f X (x)0.640.2(a)1 2 3x(b)xFigure 3. 19 The probability mass function, p X (x), <strong>and</strong> probability density function,f X (x), <strong>for</strong> Problem 3.33.3 For p X (x) <strong>and</strong> f X (x) in Figure 3.19(a) <strong>and</strong> 3.19(b) respectively, sketch roughly inscale the corresponding PDF F X (x) <strong>and</strong> show on all graphs the procedure <strong>for</strong>finding P(2 < X < 4).3.4 For each part, find the corresponding PDF <strong>for</strong> r<strong>and</strong>om variable X.(a) Case 1:0:1; <strong>for</strong> 90 x < 100;f X …x† ˆ0; elsewhere:(b) Case 2:f X …x† ˆ2…1 x†; <strong>for</strong> 0 x < 1;0; elsewhere:(c) Case 3:f X …x† ˆ3.5 The pdf <strong>of</strong> X is shown in Figure 3.20.(a) Determine the value <strong>of</strong> a.(b) Graph F X (x) approximately.(c) Determine P(X 2).(d) Determine P(X 2jX 1).1…1 ‡ x 2 ;†<strong>for</strong> 1 < x < 1:3.6 The life X, in hours, <strong>of</strong> a certain kind <strong>of</strong> electronic component has a pdf given by8< 0; <strong>for</strong> x < 100;f X …x† ˆ: 100;x2 <strong>for</strong> x 100:Determine the probability that a component will survive 150 hours <strong>of</strong> operation.TLFeBOOK

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