Help its math lol please actually know the answer

For a school newspaper article, cienna conducted a survey to find out students’ favorite subjects. she polled all the students in mrs. lopez’s advanced dance class. why is her data likely to be skewed? honors dance students are more likely to enjoy dance than students in the general population, so dance may be overrepresented. cienna should have interviewed all the students in the school to get more accurate data. honors dance students are more likely to enjoy dance than students in the general population, so dance will be underrepresented. cienna should have interviewed only every other student in the class to avoid having too many people.

Acoin bank containing only dimes and quarters has 12 more dimes than quarters. the total value of the coins is $11. how many quarters and dimes are in the coin bank?

Ineed with number 6 , explain how to get 1978