Answer:
I believe it would be 30, 100, and 1. You count them, and they're significant figures. The decimals are an estimate and cannot be measure exactly. That is what I've learned, not sure what you're learning but hopefully it helps...
Step-by-step explanation:
Basic explanation is when you count, that's an exact count. You're not estimating. That's real. But for measuring something, you wouldn't have a precise answer because it could go on forever (like Pi)... this is just what i'm assuming.