A family is in distress on an island.
They must come to shore.
They have a rowboat but it can only hold 90 kg.
They cannot swim.
How can they all get across to shore if:
Dad weighs 85 kg.
Mom weighs 65 kg.
Son weighs 45 kg.
Daughter weighs 40 kg.
Dog weighs 8 kg.
Son and daughter cross.
Daughter gets out, son returns.
Son gets out, mom and dog cross.
Mom and dog get out .
Daughter returns to get son.
Daughter and son cross.
Daughter gets out, son returns to get dad.
Son gets out, dad crosses.
Daughter returns to get son.
Son and daughter cross.