GUATEMALA CITY - Torrential rains brought by the first tropical storm of the 2010 season pounded Central America and southern Mexico, triggering deadly landslides. The death toll stood at 15 Sunday but authorities said the number could rise.
Archimedes proved the formula for the area of a circle (A = Ï r 2, where r is the radius of the circle) and showed that the value of Ï lay between 3 + 1/7 (approximately 3.1429) and 3 + 10/71 (approximately 3.1408).
The correlation coefficient, typically denoted r, is a real number between -1 and 1. The value of r measures the strength of a correlation based upon a formula, eliminating any subjectivity in the process. There are several guidelines to keep in mind when interpreting the value of r.