You apparently skipped some words and didn't copy them into the question. Fortunately, those words were part of the "red herring" section ... the part that only distracts you, and is completely unnecessary in order to answer the question.
The actual question here is: "What fraction of an hour is 7.2 seconds ?"
(7.2 sec) x (1 hour/3,600 sec) = 7.2 / 3600 = 0.002 hour .
