Passage Summary: Last year, more people showed up for the cleanup than signed up. This year, the sign-up numbers are even higher, so the organizer assumes they will definitely hit the 100-person goal again.

Conclusion: The community organizer believes this year's cleanup will be successful, meaning it will have at least 100 participants.

Reasoning: Last year, 77 people signed up and over 100 showed up; this year, 85 people have signed up.

Analysis: The organizer is making a classic LSAT mistake by assuming that a past trend will automatically repeat itself under slightly different circumstances. Just because there was a 'surplus' of walk-in volunteers last year doesn't guarantee the same will happen this year, nor does it guarantee the surplus will be large enough to reach the 100-person threshold. You should look for an answer choice that points out this reliance on the assumption that the ratio of sign-ups to actual participants will remain consistent or improve. It's a bit like assuming that because five friends showed up to your last party uninvited, you can count on five uninvited guests showing up to every party you ever throw.