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\"Tongue Piercing May speed Tooth Loss, Researchers say\" is the headline of an

ID: 3228073 • Letter: #

Question

"Tongue Piercing May speed Tooth Loss, Researchers say" is the headline of an article. The article describes a study of 56 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 size is large. The sample is voluntary. The sample is independent.

Explanation / Answer

a) here p=15/56 =0.268

hence std error =(p(1-p)/n)1/2 =0.059

for 95% CI, z=1.96

hence confidence interval =point estimate -/+ z*std error =0.1519 ; 0.3838

b)sample is a random sample

sample size is large

sample is independent