Actually, 1.5 chickens laying 3 eggs in 1 day does not imply that 1 chicken lays 2 eggs in one day. In fact, half a chicken cannot lay an egg, so if 1.5 chickens lay 3 eggs in 1 day, 1 chicken lays 3 eggs in 1 day so in 3 days 1 chicken will lay 9 eggs.