Final answer:
Without specific measurements or quantities of Rob's pencils, we cannot determine how many were longer than 5 inches. A metric ruler or a ruler with inches is the appropriate tool for measuring pencils.
Step-by-step explanation:
The student is questioning about determining how many pencils were longer than a specified length. Since pencils are small objects, the appropriate unit of measurement for their length is inches. The task is to identify pencils exceeding 5 inches in length from Rob's collection, but unfortunately, the quantity of pencils or their individual measurements are not provided in the question, making it impossible to answer accurately.
When measuring small objects like pencils, a metric ruler or a ruler with inches is the appropriate tool. Such a ruler can typically measure in millimeters, centimeters, and inches. In the absence of sufficient data, to answer how many of Rob's pencils are longer than 5 inches, additional information about the lengths of the pencils found in his desk would be necessary.