It said i got 0.5/1 and idk which one was wrong

Kayla has a $500 budget for the school party. she paid $150 for the decorations. food will cost $5.50 per student. what inequality represents the number of students, s, that can attend the party?

Acircle has a circumference of 7.850 units. what is its radius?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate. true or false?