"tongue piercing may speed tooth loss, researchers say" is the headline of an article. the article describes a study of 42 young adults with pierced tongues. the researchers found receding gums, which can lead to tooth loss, in 15 of the participants.

(a) construct a 95% confidence interval for the proportion of young adults with pierced tongues who have receding gums. (round your answers to three decimal places.)

(b) what assumptions must be made for use of the z confidence interval to be appropriate? (select all that apply.)
__the sample is a random sample.
__the sample is independent.
__the sample is voluntary.
__the sample size is large.