In a class of 30 students, everyone has either a pierced nose or a pierced ear. the professor asks everyone with a pierced nose to raise his or her hand. eight hands go up. then the professor asked everyone with a pierced ear to do likewise. this time there are 25 hands raised. how many students have piercings both on their ears and their noses?

Arandomized controlled trial is designed to evaluate the effect of metoprolol in patients with heart failure. while preparing for statistical analysis, the researcher reviews some common types of statistical errors. which of the following statements is true regarding a type i error in a clinical study? a. the study is not significantly powered to detect a true difference between study groups. bthe null hypothesis is true but is rejected in error. c. the null hypothesis is false but is accepted in error. d. type i error is also known as beta and is usually 0.1 or 0.2. e. type i error depends on the study's confidence interval.