Recitation 1 Solutions

# Recitation 1 Solutions - Steven Weber Dept. of ECE Drexel...

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Steven Weber Dept. of ECE Drexel University ENGR 361: Statistical Analysis of Engineering Systems (Spring, 2010) Recitation 1 Solutions Let k,l be integers with 1 l k . Assume the sex of a child is unaﬀected by the sexes of any siblings and that each child is equally likely to be a boy or a girl. Note there are 2 k possible gender assignments for k children. The two optional questions require the use of the binomial coeﬃcient ( s r ) , the number of ways of selecting an unordered subset of r objects from a set of s distinct objects. 1. A family has three children. What is the probability that all three are girls given that at least one is a girl? 1 7 (1) There are seven possibilities for three children with at least one girl, of these one is all girls. 2. A family has k children. What is the probability that all k are girls given that at least one is a girl? 1 2 k - 1 (2) There are 2 k - 1 possibilities for k children with at least one girl, of these one is all girls. 3.
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## This note was uploaded on 06/10/2010 for the course ENGR 361 taught by Professor Eisenstein during the Spring '04 term at Drexel.

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