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Unformatted text preview: Problem Set 3- Due Thursday 10/23/08 Econ 319 - Introduction to Probability and Statistics Fall 2008 Cornell University Prof. Molinari 1. The waiting time, in hours, between successive speeders spotted by a radar unit is a continuous random variable, X; with cumulative distribution function F ( x ) = 8 < : for x & & 1 ¡ e & 3 & ¡ x ¡ for x > ; Compute V ar ( X ) : 2. Consider two independent random variables X and Y with joint probability density function f ( x;y ) = 1 2 & e & 1 2 ( x 2 + y 2 ) : Compute Cov ( X;Y ) : 3. Suppose that the probability of a young person &nding the ¡perfect date¢in a one day internet search on a chat room is : 4 . Suppose that 20 people attempt independent ¡perfect date¢ searches over the internet on a particular day. (a) What is the probability that all of them &nd the ¡perfect date¢? (b) What is the probability that between 3 and 7 of them &nd the ¡perfect date¢?...
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- Fall '07
- Normal Distribution, Probability distribution, Probability theory, probability density function, ECON3200, Prof. Molinari