Chapter 17 Random Variables612
If there is a girl in front, behind, to the left, or to the right of a boy, then the two of
themflirt. One student may be in multiple flirting couples; for example, a student
in a corner of the classroom can flirt with up to two others, while a student in
the center can flirt with as many as four others. Suppose that desks are occupied
by boys and girls with equal probability and mutually independently. What is the
expected number of flirting couples?Hint:Linearity.
Problem 17.12.
Here are seven propositions:
x 1 OR x 3 OR x 7
x 5 OR x 6 OR x 7
x 2 OR x 4 OR x 6
x 4 OR x 5 OR x 7
x 3 OR x 5 OR x 8
x 9 OR x 8 OR x 2
x 3 OR x 9 OR x 4Note that:- Each proposition is the disjunction (OR) of three terms of the formxior the
formxi. - The variables in the three terms in each proposition are all different.
Suppose that we assign true/false values to the variablesx 1 ;:::;x 9 indepen-
dently and with equal probability.