Title 22, §87101(r)(5) defines a "Residential Care Facility for the Elderly" (RCFE), as ". . . a housing arrangement chosen voluntarily by the resident, the resident's guardian, conservator or other responsible person; where 75% of the residents are sixty years of age or older and where varying levels of care and supervision are provided, as agreed to at time of admission or as determined necessary at subsequent times of reappraisal. Any younger residents must have needs compatible with other residents.