Moreee the table shows the soil density of several soil samples at different depths. depth (m) 1 5 6 8 10 12 14 21 23 24 28 soil density ( ) 1045 1063 1102 1140 1191 1232 1249 1254 1265 1268 1273 (a) write the quadratic regression equation that models the data. let x = depth below the surface and let y = soil density. (b) use the equation to estimate the soil density of a sample at a depth of 20 m. show your work.

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.