21. A random sample of 539 households from a certain midwestern city was selected, and it was determined that 133 of these households owned at least one rearm ( The Social Determinants of Gun Ownership:

Self-Protection in an Urban Environment, Criminology, 1997: 629—640). Using a 95% con -

dence level, calculate a lower con dence bound for the proportion of all households in this city that own at least one rearm.