hw07soln - ECE 310, Spring 2005, HW 7 solutions Problem...

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Unformatted text preview: ECE 310, Spring 2005, HW 7 solutions Problem E6.7 According to what was derived in pages 182-184 of the textbook, we have, substituting n = 4, k = 2, a = 3 and b = 3: P ( K = 2) = 4 2 (6)(5)(5) (3)(3)(10) ) = ( 4! 2!2! ) 5!4!4! 2!2!9! = 2 7 Problem E6.8 a) Assuming the lifetime is exponentially distributed, F ( x ) = (1- e- x ) U ( x ): F (5000) = 1 2 1 2 = (1- e- 5000 ) = ln 2 5000 Therefore, the mean chip lifetime is 1 = 5000 ln 2 b) P ( { X < 1000 } { X > 10000 } ) = P ( X < 1000) + P ( X > 10000) = P ( X 6 1000) + (1- P ( X 6 10000)) = F (1000) + 1- F (10000) = 1- e- ln 2 5 + 1- (1- e- 2 ln 2 ) = 1- ( 1 2 ) 1 / 5 + ( 1 2 ) 2 Problem E6.10 Assuming Exponential distribution, and denoting by T the random variable corresponding to the duration of a call, we have: F T (1) = P ( T 1) = 1- P ( T > 1) = 0 . 5 But, F T (1) = 1- e- , so we have: 1- e- = 0 . 5 = ln(2) Then, P ( T > . 5) = 1- F T (0 . 5) = 1- (1- e- . 5ln(2) ) = 2- . 5...
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This homework help was uploaded on 09/26/2007 for the course ECE 3100 taught by Professor Haas during the Spring '05 term at Cornell University (Engineering School).

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hw07soln - ECE 310, Spring 2005, HW 7 solutions Problem...

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