The information in the table represents the effect of the mass of two objects on the gravitational force between the two objects.
Which number should be in the cell with the question mark?
The number is two because when you double the mass of one of the objects, the force between the objects is halved.
The number is four because when you double the mass of one of the objects, the force between the objects remains the same.
The number is eight because when you double the mass of one of the objects, the force between the objects also doubles.
The number is sixteen because when you double the mass of one of the objects, the force between the objects increases by a factor of 4.