ggplot$($credit$\_$data$\_$cleaned, aes$($duration$))+$

$+$ geom$\_$histogram$($aes$($y $=$ after$\_$stat$($density$)),$

$+$ bins$=$number$\_$bins, fill$=$"grey", col$=$"black"$)+$

$+$ geom$\_$density$($col$=$"red", lwd$=1)+$

$+$ stat$\_$function$($fun$=$dnorm, args $=$ list$($mean $=$ xbar, sd $=$ s$),$

$+$ col $=$ "blue", lwd $=1)+$

$+$ geom$\_$vline$($xintercept$=$xbar, linetype$=1,$ lwd$=1)+$

$+$ geom$\_$vline$($xintercept$=$median, linetype$=2,$ lwd$=1)+$

$+$ ggtitle$("$Histogram of duration"$)$