Jerry received both the 15th highest and the 15th lowest mark in the class. how many students are in the class?

There are 29. That is because there's 14 people before him, and 14 people after, him, and that's 28 and +1 for him and that;s 29. People often make mistakes and say that there's 30 because they count 15 before and 15 after, but there's actually 14 before and 14 after.