Grading Amusement

I'm grading my Soil Mechanics finals right now. I have a questions about Apatosaurus. Being a large dinosaur with a weight of about 28 tons, if we assume each of its four feet was 3 feet in diameter, how much stress does this dinosaur apply to the soil beneath its feet?

Students should be able to determine the total area that the dinosaur is in contact with the ground (4 x (1.5² x 3.14159) = or about 28 square feet. Their answers should be about 1 tsf (28t/28sf) - many of the students get this, but some students just skip the question. Why? I think because there's math involved, which makes me kind of sad. One student didn't skip the question, but instead wrote:

a lot, dinosaurs are huge

Thank you student. You don't get the points, but you get kudos for making me smile.