The River IQ Test

The table below illustrates how this is done (f=father, m=mother, d=daughter, s=son, p=police officer, and t=thief).

Action Left Bank Right Bank
Start f,s,s,m,d,d,p,t
Police officer and thief cross river f,s,s,m,d,d p,t
Police officer returns f,s,s,m,d,d,p t
Officer and son cross river f,s,m,d,d p,s,t
Police officer and thief returns f,s,m,d,d,p,t s
Father and son cross river m,d,d,p,t f,s,s
Father returns f,m,d,d,p,t s,s
Father and mother cross river d,d,p,t f,s,s,m
Mother returns m,d,d,p,t f,s,s
Police officer and thief cross river m,d,d f,s,s,p,t
Father returns f,m,d,d s,s,p,t
Father and mother cross river d,d f,s,s,m,p,t
Mother returns m,d,d f,s,s,p,t
Mother and daughter cross river d f,s,s,m,d,p,t
Police officer and thief return d,p,t f,s,s,m,d
Officer and daughter cross river t f,s,s,m,d,d,p
Police officer returns p,t f,s,s,m,d,d
Officer and thief cross river f,s,s,m,d,d,p,t