Maria had 20 dollar gift card to an online music store. She spent the entire amount on songs which cost 1 dollar each and the music videos which cost 2 dollars each Maria bought five more songs than music videos. Write down the system of equations to represent the situation

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.