2) Penelope Pig is eating her way through Cooter's Candy-Coated Bugs
Shop. When she got there, there were two $5.25 chocolate-covered
centipedes on the display shelf. There were also ten $2 caramel-coated
spiders and six $1.50 cockroaches dipped in white chocolate. Penelope
eats all but 3 of the candy-coated bugs. The 3 bugs she didn't eat are
worth $8.25. Which bugs were left?

Her conclusion that 90% of the student body wants the colors changed is an INCORRECT conclusion. The 90% out of 100% is not referring to the total numbers of the student body.For example, 100 people are members of student body if only 50 members responded the survey, then we have:
 90% of 50 members who answered the survey said that they want the changed.