False positives

false_positive<-function(sensitivity,specificity,prevalence){
  a<-sensitivity* prevalence
  b<- (1-specificity) * (1-prevalence)
 1- (a/(a+b))
}

sensitivity<-runif(10000000,0.9, 1)
specificity <-runif(10000000,0.9, 1)
prevalence <-runif(10000000,0.1, 0.2)

hist(false_positive(sensitivity,specificity,prevalence))