<em>Missing Information:</em>
<em>It takes Mr. Hamilton 1/15 of an hour to grade one student’s exam and 1/30 of an hour to grade one student’s quiz.</em>
Answer:

Step-by-step explanation:
Given


Required
Determine the time spent on x students
First, we need to determine the total time spent on 1 student


Take LCM



Next is to determine the total time on x students:


It's already written in scientific notation, but since it needs 2 more significant digits, it would be 3.500×10^4.
The answer to your question is,
A) 500. The only way it would be more than 500 is for the tens place to be 5 or over. :)
-Mabel <3