Uniform Random Variables are used where each outcome of an event is equally probable. For p U ( u ) = P ( U ≤ u ) {\displaystyle p_{U}(u)=P(U\leq u)} where U {\displaystyle U\,} is some [ a , b ] {\displaystyle [a,b]\,} -Uniform Random Variable, p U ( u ) {\displaystyle p_{U}(u)\,} will always be zero unless ( a ≤ u ≤ b ) {\displaystyle (a\leq u\leq b)} . When ( a ≤ u ≤ b ) {\displaystyle (a\leq u\leq b)} , then p U ( u ) = 1 b − a {\displaystyle p_{U}(u)={\frac {1}{b-a}}} .