group of rats to run down a narrow passage in a cage to receive food
in a goal box. He then put a harness on each rat and connected it to
an overhead wire attached to a scale. In this way, he could place the
rat different distances from the food and measure the pull (in
grams) of the rat toward the food. He found that the relationship be-
tween motivation (pull) and position was given approximately by
where pull p is measured in grams and distance d in centimeters.
When the pull registered was 40 grams, how far was the rat from
the goal box?